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Contents
INTRODUCTION
............................................................................................................................................
2
PROCESS SAMPLES AND ASSOCIATED REQUEST
FORMS..................................................................
3
IDENTIFY SPECIMENS AND REQUEST FORMS THAT DO NOT COMPLY WITH
MINIMUM INDUSTRY REQUIREMENTS FOR LABELLING, IDENTIFICATION AND
TEST REQUESTS
...........................................................................................
3
RECORD ANY DISCREPANCIES AND INDICATE WHAT ACTION IS REQUIRED
.......................................................... 4
LOG SAMPLES, RECORDING DETAILS THAT ALLOW ACCURATE TRACKING AND
CHAIN OF CUSTODY ...................... 4
PERFORM TESTS
.........................................................................................................................................
6
SELECT AUTHORISED TESTS INDICATED FOR THE REQUESTED
INVESTIGATIONS ................................................
6
COMMON CHEMICAL PATHOLOGY TESTS
.........................................................................................................
7
CONDUCT INDIVIDUAL TESTS, OR BATCHES OF TESTS, ACCORDING TO
DOCUMENTED METHODOLOGIES, APPLYING REQUIRED QUALITY CONTROL
PROCEDURES
.................................................................................................
12
MANAGE TASKS AND ORGANISE WORK TO ENSURE EFFICIENT USE OF TIME
..................................................... 13
FLAG TEST RESULTS THAT ARE OUTSIDE ACCEPTED QUALITY CONTROL
LIMITS ................................................ 13
APPLY QUALITY CONTROL PROCESSES TO DISCRIMINATE BETWEEN
SIGNIFICANT DATA AND ARTEFACT ............. 14
CONFIRM WITH SUPERVISOR ANY FURTHER TESTING REQUIREMENTS
.............................................................
16
RECORD ALL TEST DATA, NOTING ANY PHENOMENA THAT MAY BE RELEVANT
TO THE TREATMENT OF DATA OR THE INTERPRETATION OF RESULTS
......................................................................................................................
16
MAINTAIN LABORATORY RECORDS
.......................................................................................................
17
RECORD ENTRIES ON REPORT FORMS OR INTO A LABORATORY INFORMATION
MANAGEMENT SYSTEM, ACCURATELY CALCULATING, RECORDING OR
TRANSCRIBING DATA AS REQUIRED
............................................. 17
ENSURE SAMPLES AND ASSOCIATED PAPERWORK MAINTAIN TRACEABILITY
THROUGHOUT TESTING .................. 18
LEGAL AND ETHICAL RESPONSIBILITIES
.........................................................................................................
19
ENVIRONMENTAL SUSTAINABILITY
................................................................................................................
20
BIBLIOGRAPHY
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21
DOCUMENT REVISION
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23
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Introduction
Anatomy is the study of the structure of organisms and their
parts, and humans have many parts that don’t always function or
look in what would be referred to as a standard way.
Biological systems are inherently prone to abnormal anatomy,
with some being innocuous, such as the case of unusually long heel
bones (calcanei) giving calf muscles superior leverage and has been
observed in successful sprinters for years (Ingraham, 2019). Other
cases are more serious such as spina bifida where there is
incomplete closing of the spine and membranes around the spinal
cord during early development which can result in mild to severe
physical and intellectual disabilities (Centers for Disease Control
and Prevention, 2019).
Chemical pathology is the study of chemical and biochemical
mechanisms of the body relating to disease, through the use of
chemicals present in body fluids (such as blood or urine) and
tissues.
Normal chemical levels are based on averages from numerous
patients or based on an individual’s historical levels. Many
diseases cause significant changes in the chemical composition of
body fluids including raised blood enzymes due to their release
from heart muscles after a heart attack, or increased blood sugar
in diabetes mellitus due to lack of insulin.
Chemical pathology involves (Pūtaiao, 2019):
• general or routine chemistry – common blood chemistries such
as electrolytes, blood gases, lipids, liver and kidney function
tests.
• special chemistry – more elaborate techniques such as
electrophoresis and manual testing methods.
• clinical endocrinology – the study of hormones and diagnosis
of endocrine disorders.
• detection and measurement of drug levels –
o toxicology - analysis testing of the levels for drugs of abuse
and other chemicals, which indicate the medical risk and required
treatment.
o therapeutic drug monitoring – measurement of therapeutic
medications in blood levels to optimise dosage.
• urinalysis – chemical analysis of urine.
• faecal analysis – commonly done for the detection of
gastrointestinal disorders.
• toxin detection – aids in determining the appropriate medical
treatment and helps identify patients that would benefit from
antibiotic treatment, reducing the unnecessary use of
antibiotics.
Gel electrophoresis
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• Immunoassays – chemical tests used to detect or quantify a
specific substance or analyte in a blood or body fluid sample using
an immunological reaction. These tests can be used to detect
antigens for the identification of hepatitis B and chlamydia, as
well as the detection of antibodies produced in HIV, viral
hepatitis and Lyme disease (Advameg Inc, 2020).
The quality of chemical pathology laboratories has increased
immensely as technology has improved allowing for more accurate
results and shorter turn-around-times. Automation was one of the
big advancements in the field allowing for increased productivity,
reducing errors and improving safety (Streitberg, et al., 2009).
This became possible because of the development of the continuous
flow analyser in the 1950’s (Felder, 2014). Currently automation
encompasses specimen transportation, sorting, accessioning and
inspection.
Process samples and associated request forms
At the completion of this section, you should be able to:
• Identify specimens and request forms that do not comply with
minimum industry requirements for labelling, identification and
test requests
• Record any discrepancies and indicate what action is
required
• Log samples, recording details that allow accurate tracking
and chain of custody.
Identify specimens and request forms that do not comply with
minimum industry requirements for labelling, identification and
test requests Many different samples may arrive at your laboratory
for testing and/or examination. No matter how they arrive, a key
feature of all samples for testing will be an accompanying request
form, card, or sheet.
Before commencing any test work, you are required to check all
the details of the request to ensure you have the correct samples
and that you know which test methods and equipment are needed.
There will be a routine system in your workplace that tells you
what samples or materials are to be tested and what tests are to be
done on them. This could be through a Laboratory Information
Management System (LIMS), spreadsheet or test sheets with priority
dates.
Test sheets may show a unique serial number for each sample
enabling you to identify and locate the sample via the serial
number on its label. Test sheets may also provide a code, barcode
or description of the material that will help in the identification
of the sample
Labels and codes on samples should allow you to link the sample
to its source (such as a patient), identify what the sample is
(cerebrospinal fluid (CSF), serum, semen etc.), determine which
samples are to be tested and which tests are to be carried out.
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If you identify any sample or request forms that do not comply
with minimum industry requirements for labelling, identification
and test requests, they must be recorded and reported to your
supervisor. Follow your organisation's policies and procedures to
record and report.
Record any discrepancies and indicate what action is required
Where documentation such as test requests or identifying codes or
markers are identified as incorrect or suspected to be incorrect,
action must be taken to correct the discrepancy, or to replace the
document and/or sample.
Despite all efforts, occasionally the sample is not suitable.
This is not always obvious until sample preparation has commenced.
Apart from checking that the correct collection vessel has been
used, and the correct specimen has been collected, you also need to
note the condition of the sample. The trauma that can occur at
collection of samples can lead to haemolysis of the serum or plasma
sample or a bloodied CSF collection.
There could also be damage to the container in transit.
Haemolysis is the rupturing (lysis) of red blood cells
(erythrocytes) and the release of their contents (cytoplasm) into
surrounding fluid (e.g. blood plasma). Haemolysis can be
caused:
• by complications during blood collection such as unsecure line
connections, contamination, incorrect needle size, improper tube
mixing and incorrectly filled tubes.
• by the effects of mechanical processing.
• by bacterial action in cultured blood specimens.
The affects can include increases in potassium, phosphate,
bilirubin, aspartate aminotransferase (AST) and decreases in
troponin T and glucose.
If the sample label does not match the request the test cannot
be carried out. When samples are not as expected, or appear
atypical, immediately record your observations and report them to
your supervisor or other appropriate person.
You will need to request an additional sample or samples for
testing and reject the faulty samples. Performing tests on faulty
samples is a waste of time as the results may be misleading,
resulting in a potential misdiagnosis.
Log samples, recording details that allow accurate tracking and
chain of custody When samples arrive in your laboratory or are
extracted from a patient they should be inspected for quality, and
the specific sample data recorded. Your laboratory may use a LIMS
or a manual log entry system for this.
Some laboratories may use a combination of systems. This may be
due to legal requirements (that is, a particular system must be
used by law), laboratory standard or accreditation requirements
(ISO/IEC), or simply because there are not any acceptable
commercial programs available which are useful for your particular
laboratory. MS Excel is another tool for recording sample
information.
Normal (N), Slight (1+), Moderate (2+ to 3+) and Grossly
(4+)
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It is important to check that you are authorised to record
information onto the documents in your laboratory. An SOP or
quality manual contains details about who can mark documents. Your
laboratory may have special procedures for correcting mistakes or
illegible recordings.
You should check these with your laboratory supervisor. Some
documents may be controlled documents, for example methods or SOPs,
and these cannot be amended without approval from the laboratory
supervisor and/or quality manager.
It is vital to ensure correct and complete information for
‘chain of custody’ to avoid any doubt about the integrity of
specimens. Chain of custody is the chronological documentation
showing the collection, transfer, receipt, analysis, storage and
disposal of the specimen.
It should be possible to know the entire history of the
specimen; from original collection (including who took the sample
and who has handled it during its journey to and throughout your
laboratory), through to the completion of any test. Confusion over
labelling of samples could lead to time wasted through wrong tests
being performed, results going to the wrong client or incompatible
products being transfused. This can also affect commercial aspects
such as billing details and business reputation.
You may be required to add labels or designate identification
numbers or codes to the samples. This is to allow for successful
sample tracking and to assist in traceability/tracking throughout
sample preparation, testing and other stages in your
laboratory.
The laboratory’s capacity to protect sensitive information may
be required by law or as a condition of registration or
accreditation. The procedures and policies relating to security and
confidentiality ensure that customers and clients have confidence
in the laboratory.
Storage of samples
Biological specimens are fragile and often degrade reasonably
quickly when maintained at room temperature and may still lose
integrity if they undergo multiple freeze-thaw cycles. Ideal
storage temperatures vary depending on the biological material, the
solution it is suspended in, the samples intended use and the time
it will be stored (Brooks Life Sciences, 2018).
Tissue and organ samples may be preserved via fixation using
formalin. The cells may lose their biological function, but the
visual appearance of the tissue is preserved. This has been the
traditional method of preservation for routine histological
examinations that involve paraffin embedding, sectioning (cutting
into very thin slices), chemical staining and microscopic
examination of the sample.
When a sample is to be examined both for its appearance and
certain biological properties, formalin, followed by paraffin
embedding cannot be used. Instead a fresh sample must be supplied.
This means that the sample must be preserved in some other way.
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Another method of preservation involves removing the tissue and
immediately freezing it. This must be done quickly to prevent ice
crystals from forming as ice crystals will rupture cells. The types
of tests that may require a frozen section all have one thing in
common: the tissue must be as close to in vivo conditions as
possible.
However, one distinct advantage of formalin preservation and
paraffin embedding is that infectious agents, such as viruses, and
in particular human immunodeficiency virus or HIV, are inactivated
by formalin and paraffin embedding. Therefore, those working on
highly dangerous tissue material are protected. If a sample is
incorrectly prepared or shows sign of deterioration it must be
safely disposed of and a new sample requested.
Samples in containers or tubes which are cracked or leaking
represent a hazard not only to the collector, but the samples
themselves may be contaminated (or have contaminated other samples)
and this may affect any examination or test to be performed.
Once damaged or leaking samples are detected, they should be
isolated and separated from other samples. The samples which have
come into contact with them should also be carefully examined for
damage or contamination. Even if samples appear not to be
contaminated it should be noted what type of spill, breakage or
leakage occurred with other samples in that batch. This way any
anomalous results can be explained.
Your workplace/laboratory should have an SOP for isolating and
controlling sample leaks, spills. This procedure is in place to
minimise the risk of cross-contamination and maintain sample
integrity. The procedure may also require you to report these
events to your workplace/laboratory supervisor.
Perform tests
At the completion of this section, you should be able to:
• Select authorised tests indicated for the requested
investigations
• Conduct individual tests, or batches of tests, according to
documented methodologies, applying required quality control
procedures
• Manage tasks and organise work to ensure efficient use of
time
• Flag test results that are outside accepted quality control
limits
• Apply quality control processes to discriminate between
significant data and artefact
• Confirm with supervisor any further testing requirements
• Record all test data, noting any phenomena that may be
relevant to the treatment of data or the interpretation of
results.
Select authorised tests indicated for the requested
investigations Chemical pathology as a sub-speciality within
pathology that extends across most medical specialities. It
involves the chemical analysis of bodily fluids such as blood
(whole blood, serum or plasma), urine, cerebrospinal fluid,
effusions, seminal fluid, sweat and amniotic fluid to assist in the
diagnosis of various disease processes.
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There are numerous tests that can be requested for
investigation. You must select the tests that have been indicated
and then conduct the tests according to documented methodologies,
applying required quality control procedures.
The chemical pathologist must understand a wide variety of
physico-chemical techniques, be able to solve problems that arise
in the laboratory and make informed decisions with regard to the
selection of instrumentation.
Common chemical pathology tests
Liver function tests
Liver function tests (LFTs) is a group of tests that are
performed together to detect, evaluate, and monitor liver disease
or damage. LFTs measure enzymes, proteins, and substances that are
produced or excreted by the liver and are affected by liver injury.
Some are released by damaged liver cells and some reflect a
decrease in the liver's ability to perform one or more of its
functions.
When performed together, these tests give the doctor a snapshot
of the health of the liver, an indication of the potential severity
of any liver injury, change in liver status over time, and a
starting place for further diagnostic testing. Examples of tests
performed as part of a LFT include:
• Alanine aminotransferase (ALT) test – an enzyme mainly found
in the liver; the best test for detecting hepatitis.
• Alkaline phosphatase (ALP) test – an enzyme related to the
bile ducts; often increased when they are blocked.
• Aspartate aminotransferase (AST) test – an enzyme found in the
liver and a few other places, particularly the heart and other
muscles in the body.
• Total bilirubin test – measures all the yellow bilirubin
pigment in the blood. Another test, direct bilirubin, measures a
form combined with another compound in the liver and is often
requested with total bilirubin in infants with jaundice.
• Albumin test – measures the amount of albumin in your blood
which is the main protein made by the liver and tells whether or
not the liver is making an adequate amount.
• Gamma-glutamyl transferase (GGT) test - an enzyme found mainly
in the liver and is a useful marker for detecting bile duct
problems.
• Total protein test - measures albumin and all other proteins
in blood, including antibodies made to help fight off infections.
An increased result can be due to multiple myeloma, dehydration,
chronic liver disease, chronic inflammation or infection. A
decreased result can be due to malnutrition, severe liver disease,
water overload, nephrotic syndrome, or protein-losing
enteropathy.
LFT results are not diagnostic of a specific condition; they
indicate that there may be a problem with the liver. In a person
who does not have symptoms or identifiable risk factors, abnormal
liver test results may indicate a temporary liver injury or reflect
something that is happening elsewhere in the body – such as in the
skeletal muscles, pancreas, or heart. It may also indicate early
liver disease and the need for further testing and/or periodic
monitoring.
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Results of LFTs are usually evaluated together. Several sets of
results from tests performed over a few days or weeks are often
assessed together to determine if a pattern is present. Each person
will have a unique set of test results that typically change over
time. A doctor evaluates the combination of liver test results to
gain clues about the underlying condition. Often, further testing
is necessary to determine what is causing the liver damage and/or
disease.
The table below shows examples of some combinations of results
that may be seen in certain types of liver conditions or
diseases.
Type of liver condition or disease
Bilirubin ALT and AST ALP and GGT Albumin
Acute Liver damage (due, for example, to infection, toxins or
drugs, etc.)
Normal or increased usually after ALT and AST are already
increased
Usually greatly increased; ALT is usually higher than AST
Normal or only moderately increased
Normal
Chronic forms of various liver disorders
Normal or increased
Moderately increased
Normal to slightly increased
Normal
Alcoholic Hepatitis
Normal or increased
AST is usually higher than the level of ALT
Normal or moderately increased, GGT markedly increased
Normal
Cirrhosis May be increased but this usually occurs later in the
disease
AST is usually higher than ALT but levels are usually lower than
in alcoholic disease
Normal or increased
Usually decreased
Bile duct obstruction, cholestasis
Normal or increased; increased in complete obstruction
Normal to moderately increased
Increased; often greater than 4 times what is normal
Usually normal but if the disease is chronic, levels may
decrease
Cancer that has spread to the liver (metastasized)
Usually normal Normal or slightly increased
Usually greatly increased
Normal
Cancer originating in the liver (hepatocellular carcinoma,
HCC)
May be increased, especially if the disease has progressed
AST higher than ALT but levels lower than that seen in alcoholic
disease
Normal or increased
Usually decreased
Autoimmune Normal or increased
Moderately increased
Normal or slightly increased
Normal or decreased
http://www.labtestsonline.org.au/learning/Glossary/chronichttp://www.labtestsonline.org.au/learning/Index-of-Conditions/hephttp://www.labtestsonline.org.au/learning/Index-of-Conditions/hephttp://www.labtestsonline.org.au/learning/Glossary/cirrhosis
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The quantitative human chorionic gonadotropin (hCG) blood test
measures the level of hCG hormone present in a sample of blood. hCG
is a hormone that is produced during pregnancy and the test is
performed to:
• confirm pregnancy
• determine the approximate age of the foetus
• diagnose an abnormal pregnancy, such as an ectopic
pregnancy
• diagnose a potential miscarriage
• screen for Down’s syndrome.
Blood tests
A full blood count (FBC) is one of the most commonly ordered
tests and provides important information about the kinds and
numbers of cells in the blood: red blood cells (RBC), white blood
cells (WBC), platelets and mean corpuscular volume (MCV) which is a
measurement of the size of RBCs.
Abnormalities in any of these types of cells can indicate the
presence of important medical disorders. Anisocytosis is a
condition in which the RBCs are
unequal in size. This is commonly found in anaemia and other
blood conditions.
The RBCs of an individual contain antigens on their surfaces
that correspond to their blood group and antibodies that will
attack antigen sites on the surfaces of RBCs of another group. For
example, someone with blood type A has the A antigen on its RBCs
and antibodies (Anti-B) that will attack RBCs with the B antigen on
them. The reaction between RBCs and corresponding antibodies
usually results in clumping (agglutination) of the RBCs.
Blood cholesterol testing measuring the level of cholesterol in
the blood may be performed if the patient already knows they have
heart disease (angina, heart attack), or if there is a family
history of heart disease at an early age. An increased result can
be due to familial hyperlipidaemia, hypothyroidism, liver disease,
renal disease, diabetes mellitus whereas a decreased result can be
due to hyperthyroidism, infection, myocardial infarction or
inherited hypolipidaemias.
Glucose tolerance test
A glucose tolerance test (GTT) determines whether or not blood
glucose levels are within the reference range; to screen for,
diagnose, and monitor diabetes and gestational diabetes mellitus
(GDM). An increased glucose result can be due to a non-fasting
state, diabetes mellitus, infection, excess endogenous or exogenous
steroid. A decreased result may be due to excess exogenous or
endogenous insulin, early glucose intolerance, adrenal or pituitary
failure, severe liver disease or oral hypoglycaemic medication.
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DNA testing
Deoxyribonucleic acid (DNA) is a molecule that carries the
genetic instructions used in the growth, development, functioning
and reproduction of all known living organisms and many viruses.
Fluorescence in situ hybridisation (FISH) is a molecular testing
method that uses fluorescent probes to evaluate genes and/or DNA
sequences on chromosomes.
Immunological tests
Immunological tests can be conducted to detect and measure a
number of different components in the body such as drugs, hormones,
specific proteins, tumour markers and markers of cardiac injury
(Advameg Inc, 2020). These tests all work on the principle of an
immunological reaction which is the formation of an
antibody-antigen complex. The immune system is one of the main
lines of defence for the body and involves the use of white blood
cells known as leukocytes.
These leukocytes travel through the bloodstream and into
tissues, attacking microorganisms, parasites and other materials
the body identifies as foreign (Delves, 2019). To be effective, the
immune system must be able to identify what belongs to the body
(self) and what does not (foreign).
There are two types of immunity the immune system provides:
• Innate immunity – is an immunity that is present from birth
and does not have to be learned through exposure to an invader. The
white blood cells involved in innate immunity are monocytes,
neutrophils, eosinophils, basophils and natural killer cells.
• Acquired (adaptive or specific) immunity – is not present at
birth but is learned. Learning occurs when the immune system of a
person encounters invaders and recognises foreign substances
(antigens). The components of acquired immunity then learn the best
way to attack each antigen and begin to develop a memory for
it.
Acquired immunity can take some time to develop after the first
exposure, however, afterwards the antigen is remembered, and
successive responses will be quicker and more effective. The white
blood cells responsible for acquired immunity are lymphocytes (T
cells and B cells).
Both mechanisms still use antibodies also known as
immunoglobulin, which are proteins produced by white blood cells
called B cells. The antibodies tightly bind to the epitope of an
invading antigen, tagging the invader for attack or directly
neutralising it. An antigen is any substance the immune system can
recognise and that can therefore stimulate an immune response.
Antigens can have multiple different epitopes meaning that a
number of different antibodies can bind to and attack the same
antigen. Polyclonal antibodies are a heterogenous mixture of
antibodies with varying antigen binding sites which will bind to
varying epitopes of the same antigen.
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Monoclonal antibodies are a set of identical antibodies that
bind to the same epitope of an antigen. Monoclonal antibodies are
produced ex vivo using tissue culture techniques while the
polyclonal antibodies are produced in live animals. Monoclonal
antibodies provide good batch to batch homogeneity and a reduced
probability of cross reactivity to other antigens compared to their
polyclonal counterparts (labclinics, 2018).
Antibodies consist of four polypeptides, two heavy chains and
two light chains joined to form a “Y” shaped molecule (The
University of Arizona, 2000). The amino acid sequence at the tips
of the “Y” vary greatly for different antibodies. This is known as
the variable region and is made up of between 110-130 amino acids.
This variation gives the antibody it’s specificity for binding to
different antigens.
The mechanism for destroying antigens is determined by the
constant region, which defines which of the five classes an
antibody is allocated to – IgM, IgG, Iga, IgD or IgE.
Each antibody is specifically designed to bind to a particular
antigen in a lock and key like mechanism. This is the first stage
of reactions between antibodies and antigens, of which there are
three:
1. Formation of an antigen-antibody complex
2. Visible events such as precipitation and agglutination.
3. The destruction or neutralisation of the antigen.
The different immunoassay test methods are summarised below
(Advameg Inc, 2020).
Immunoprecipitation.
The simplest immunoassay method measures the quantity of
precipitate, which forms after the reagent antibody (precipitin)
has incubated with the sample and reacted with its respective
antigen to form an insoluble aggregate. Immunoprecipitation
reactions may be qualitative or quantitative.
Particle immunoassays.
By linking several antibodies to the particle, the particle is
able to bind many antigen molecules simultaneously. This greatly
accelerates the speed of the visible reaction. This allows rapid
and sensitive detection of antibodies that are markers of such
diseases, as infectious mononucleosis and rheumatoid arthritis.
Immunonephelometry.
The immediate union of antibody and antigen forms immune
complexes that are too small to precipitate. However, these
complexes scatter incident light and can be measured using an
instrument called a nephelometer. The antigen concentration can be
determined within minutes of the reaction.
Radioimmunoassay (RIA)
A method employing radioactive isotopes to label either the
antigen or antibody. This isotope emits gamma rays, which are
usually measured following removal of an unbound (free) radiolabel.
The major advantages of RIA, compared with other immunoassays, are
higher sensitivity, easy signal detection, and well-established,
rapid assays.
The major disadvantages are the health and safety risks posed by
the use of radiation and the time and expense associated with
maintaining a licensed radiation safety and disposal program. For
this reason, RIA has
Antibody Structure (The University of Arizona, 2000)
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been largely replaced in routine clinical laboratory practice by
enzyme immunoassay.
Enzyme (EIA) immunoassay
This method uses an enzyme to label either the antibody or
antigen. The sensitivity of EIA approaches that for RIA, without
the danger posed by radioactive isotopes. One of the most widely
used EIA methods for detection of infectious diseases is the
enzyme-linked immunosorbent assay (ELISA).
Fluorescent immunoassay (FIA)
A method which utilise a fluorescent label or an enzyme label
which acts on the substrate to form a fluorescent product.
Fluorescent measurements are inherently more sensitive than
colorimetric (spectrophotometric) measurements. Therefore, FIA
methods have greater analytical sensitivity than EIA methods, which
employ absorbance (optical density) measurement techniques.
Chemiluminescent immunoassays
Utilising a chemiluminescent label. Chemiluminescent molecules
produce light when they are excited by chemical energy. These
emissions are measured by a light detector.
Conduct individual tests, or batches of tests, according to
documented methodologies, applying required quality control
procedures For all the tests mentioned previously there will be
documented methodologies for you to follow. This is to ensure all
tests whether carried out individually or as a batch of tests are
completed consistently. If different staff members are to carry out
the same test they should all follow the same methodology carrying
out the test in the exact same way.
This means that all results should be comparable regardless of
who completed the analysis and when it was done. A way of further
ensuring the reliability of results is the use of a quality control
system.
A quality system is formally described as 'the organisational
structure, responsibilities, procedures, processes and resources
for implementing the management of quality'. Said in a simpler way,
a quality system concerns the way an enterprise goes about running
its business to achieve its goals. The quality system would usually
be documented and is often based around a quality manual that
defines and embodies the system.
A very important part of a laboratory’s quality system is
quality control.
Quality control (QC) is defined as being “the operational
procedures in place to check the quality of products and services”.
In effect, these operational procedures include:
• checking a process at appropriate stages to ensure it stays
within defined limits (such as to produce the 'right' quality
product)
• eliminating the causes of any unsatisfactory performance
(reducing the rework and waste that otherwise cost companies
money)
• removing or repairing any defective products before they get
to the customer.
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QC procedures generally involve:
• measurement of a parameter
• the concepts of accuracy and precision regarding that
measurement
• a range of acceptance (i.e. the defined limits of quality)
• recording of raw data, calculations and the decision to accept
or reject
• recording of QC parameters to follow patterns over time.
Manage tasks and organise work to ensure efficient use of time
Planning is vital for completing tasks efficiently and on time as
it can reduce any potential work flow issues. These may include
being unable to use an instrument as it was already booked, and you
failed to check the roster or running out of reagents as you didn’t
check and maintain the inventory. This can result in late results
or even going beyond holding times.
Some things you could do to aid in being prepared and planned
for upcoming work include:
1. List your tasks and rate each according to priority. Then
complete the tasks in order of highest priority.
2. Sometimes to ensure efficient use of time it may be necessary
to perform tests in batches. When performing tests in batches group
samples that have similar testing requirements such as:
o incubation temperature
o additives
o centrifugation
o monitoring - how you monitor samples may be a useful way of
grouping them as well. Particularly if samples require the same
incubation or other steps to be performed at the same time.
Flag test results that are outside accepted quality control
limits The use of quality control data collected throughout testing
indicates the accuracy and precision of the test. This data is
collected through the use of:
• Blanks – Corrects for the effect of the reagents added and the
instrument used
• Standards – Check the accuracy
• Precision Checks (Duplicate Samples) – Check the precision
• Control charts – Identify trends in data
• Alternative methods – Checks the validity of the method.
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Blank samples:
A blank sample is created by adding all reagents (chemicals)
that we add to our samples and treating the blank sample in the
same way that the rest of the samples are treated. This allows us
to see what the effects from the reagents and the equipment we use
are and to subtract any interferences.
Standards:
Sample(s) of known concentration used to assess the accuracy of
an analytical run. Standards covering varying concentrations (low,
medium & high) can be used when analysing a range of analyte
concentrations in the test samples.
Precision check samples:
A sample containing the analyte at a known concentration (could
use a check sample). The same precision check sample is run a
number of times (replicates) and the range of values obtained gives
an indication of the precision, or repeatability, of the run.
Test results outside accepted quality control limits
Results that are outside quality control limits must be flagged
and all affected sample results closely checked. The cause of the
non-conforming results must be identified, and it may be necessary
to rerun some samples.
Errors in a chemical pathology laboratory come in many forms and
can be classified as pre-analysis and post-analysis (Dilworth, et
al., 2014). Pre-analysis errors include inappropriate order entry,
specimen mis-identification, sorting, aliquoting and pipetting
errors. While post-analysis errors may include erroneous data
validation, excessive turn-around-time, data entry problems and
incorrect interpretation. Corrective action will vary depending
upon the error but may involve retesting, further quality controls,
seeking assistance or further training.
Store unused sample for possible future reference
Requests for sample retesting may occur such as during legal
trials or flagged results. It is therefore imperative that any
unused sample is correctly stored so as the integrity of the sample
is maintained.
Workplace storage procedures for individual samples must be
followed as each sample may require different conditions. For
example, some may be stored in the freezer, in the fridge, away
from light or away from other samples.
Apply quality control processes to discriminate between
significant data and artefact The use of historical trends or
control charts can help with the decision as to whether a result
outside the norm is correct or if an error has occurred.
Control or run charts are graphs that show the result of testing
over time. They are called Control Charts as they are used to
‘control’ (as in quality control) a process. They can be used to
make sure that a product or process complies with QA
requirements.
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The normal situation is for a random arrangement of points on
either side of the target. There should be no points outside of the
upper or lower target limits – the process or product is said to be
within specification. This process is stable with all values near
the target – this represents acceptable quality.
When a value does appear outside of the target limits (either
above the upper or below the lower limits) you should investigate.
This variation is probably a special cause because this is not
normal for the system.
This process begins with a normal variation pattern, then with a
point outside of the limits. This is not normal for the system.
There is probably a special cause such as broken or poorly adjusted
equipment. Prompt action has fixed the problem and the system has
been brought back within target again.
If you collect data over a period of time you will be able to
see what the values usually are when the process is working
normally, so you can recognise when it is malfunctioning. If the
results are within the normally accepted limits, it is highly
probable that they are correct.
If they are outside of the normal limits, you should report the
result to your supervisor and investigate the cause. It may be that
the result is correctly showing an alteration of the process. It
may also be that the process is normal, but there is an error that
has been made in testing or recording of the result.
You should also be familiar with possible causes of increased or
decreased results such as increased iron results due to oral iron,
haemochromatosis or gastrointestinal bleeding. And decreased iron
results due to iron deficiency, infection, chronic
inflammation.
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Confirm with supervisor any further testing requirements If you
have had to flag results that are outside the accepted quality
control limits it is necessary to determine what has caused the
results. It could have been due to either the sample, method or
instrument. A testing variation investigation may be necessary, and
you should confirm with your supervisor any further testing
requirements.
Record all test data, noting any phenomena that may be relevant
to the treatment of data or the interpretation of results The word
'data' refers to the results of tests, measurements or analyses.
Data is obtained when you calibrate instruments and when you sample
or test products. Data can be:
• Quantitative – data are measurements and are written as
numbers.
• Qualitative – data are descriptions of samples.
Data must be processed, presented and stored so that it can be
found when it is needed. For example, the data obtained from
swabbing and plating equipment and surfaces around a plant is
recorded and stored. The results can then be compared from time to
time to see if there is any change in workplace and product
hygiene. If the results showed an increase in bacteria, then urgent
action may be required.
If a product or item of equipment fails a test, this must be
noted. You should also start the appropriate procedures. For
example, if an instrument is calibrated and found not to meet
tolerances (acceptable range) and cannot be adjusted, it must be
marked as defective and not used until it has been repaired or
replaced.
All test data must be recorded even if it is outside
specifications. Unusual data can highlight issues with the sample,
method or equipment and must be investigated.
It is also important to be aware of causes of increased or
decreased results such as artefacts, disease or diets. Ion blood
tests can be indicators for specific conditions that a patient may
be suffering, for example:
• Increased sodium can be due to water loss through dehydration,
diabetes or insipidus. A decreased sodium results can be due to
water overload (eg cirrhosis, congestive cardiac failure (CCF),
inappropriate antidiuretic hormone secretion (SIADH) or salt loss
(e.g. diuretic therapy, adrenal failure, gut or sweat loss, renal
impairment).
• Increased potassium could be due to oral overload, cell
leakage (sepsis or post-collection), renal disease, acidosis
(ketoacidosis, lactic acidosis) or Haemolysis. A decrease could be
due to diuretic deficiency, renal tubular disease, steroid excess,
gut loss or insulin effect.
• Increased calcium could be due to primary hyperparathyroidism,
certain types of cancer, kidney or adrenal gland failure,
sarcoidosis and medication or supplements. A decrease could
attributed to hypoparathyroidism, kidney failure, pancreatitis,
medications and low levels of albumin in the blood, which may
indicate malnutrition or liver disease.
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Maintain laboratory records
At the completion of this section, you should be able to:
• Record entries on report forms or into a laboratory
information management system, accurately calculating, recording or
transcribing data as required
• Ensure samples and associated paperwork maintain traceability
throughout testing
Record entries on report forms or into a laboratory information
management system, accurately calculating, recording or
transcribing data as required All results must be recorded and
reported, including atypical or unusual results.
All data must be reliably recorded in a way that allows other
people to find it and read it later. Results may be recorded
straight onto a LIMS, into software such as Excel, onto test sheets
or workbooks. All records must be legible and traceable.
Data obtained from dilutions, culturing, sensitivity testing and
counting must be recorded with at least the following
information:
• Name or ID of the sample, growth conditions and any tests
conducted
• The name of the person responsible for the sampling, culturing
or testing
• The time and/or date of when the sampling, culturing or
testing was done
• The results and any conclusions from analysis, for example,
reduced potassium ion concentration indicates effectiveness of
treatment
Test results hand written on a result sheet or form should be
transcribed into a computer database from which printed reports or
statistical charts can be generated. In some large workplaces,
where the testing apparatus is linked to a central computer, the
results are automatically logged as soon as the measurements are
taken.
Accurate transcription of data
If you don’t write down results accurately, mistakes occur,
resulting in transcription and transposition errors.
A transcription error occurs when a number from one sheet is
incorrectly copied to another sheet or into a computer database
program. Typically, a different digit is copied, or a number is
written in the wrong space. It is better to write measurements and
results directly onto data sheets instead of onto scraps of
note-paper during your work.
Examples:
• when 1234 is written as 1254
• wet and dry masses may have been swapped for weighing
• when plate counts are written against the wrong swab
samples.
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Transposition errors are when the order or position of digits in
a number are incorrectly recorded or the decimal point is
incorrectly placed.
These errors become a more common fault when working quickly or
under pressure. These errors are difficult to spot later because
all the same digits are still there.
Examples:
• when 7892 is written as 7982
• when 11.12 is written as 111.2.
To prevent mistakes:
• record measurements on data sheets as soon as possible (for
example, take the datasheet to the instrument)
• double-check you have entered the correct figure
• plan work time to attend to reports.
With most of the current complex instrumental techniques the
results are automatically entered into the LIMS for their
associated sample. The most likely transcription errors involve
associating dilution factors with the wrong sample or incorrect
sample labelling which could result in loading errors of samples
into the autosampler.
Ensure samples and associated paperwork maintain traceability
throughout testing Traceability is generally the ability to track a
sample from when it is collected, all the treatments and analysis
it undergoes and who has carried them out. The requirements of
document control and tracking may include:
• Collector/sampler/tester ID
• Test identification
• Date of test
• Number of tests
• Attaching the test request to samples
• Affixing stickers, labels or other code indicators. Any
mistakes should not be erased from the test sheet, instead a line
should be put through the data with your initial, date and a note
as to why it was rejected. This is standard procedure throughout
industry. It is important to ensure all equipment that can have an
effect on the accuracy or validity of test results is properly
calibrated and in good working order.
The traceability system involves both keeping a register of
blood products issued in the hospital and recording transfused
product details on the patient's file (Victoria State Government,
2008).
Information storage systems must also enable tracking back from
the recipient to the donation or batch number and thus back to the
laboratory. Laboratory records must therefore be compatible with
records of the supplying blood service.
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Plasma fractionators and the supplying blood service will also
retain records to allow the tracking of any given product or
component to the donor and from any donor to the destination of any
issued product.
However, where traceability for blood samples differ to standard
laboratories is the potential requirement to trace a path between
donor and recipient many years after transfusion (Victoria State
Government, 2008). This requires hospitals, blood banks and
laboratories to retain complete and compatible patient records for
many years after they have completed the transfusions.
Legal and ethical responsibilities Ethics are of vital
importance in pathology. No new scientific or technological
development can claim immunity from ethical scrutiny. More
specifically, moral & ethical concerns are of considerable
importance in influencing public attitudes towards pathology
The ethical requirements of pathology laboratories are outlined
by the Department of Health Standards:
• S1.1 The wellbeing of patients and confidentiality of patient
information must be primary considerations in the operation of a
pathology service.
• S1.2 The laboratory must have policies and procedures for
ensuring the protection of confidential information.
• S1.3 The laboratory must have policies and procedures to
ensure that staff treat human samples, tissues or remains with due
respect.
Laboratories may have other ethical requirements particular to
their organisation, however these are general standards that should
be adhered to by all laboratories working in the pathology
services.
Professional ethics are the moral bonds that link a profession,
the people it serves, and society. The patient’s welfare is
paramount in clinical research and healthcare ethics. This includes
maintaining privacy and confidentiality with what can be sensitive
information.
Unethical behaviours may include, but are not limited to:
• Falsifying results
• Changing recorded dates and times
• Changing sample labels or other documentation such as test
request forms.
• Discussing tests and test results with unauthorised
people.
All pathology laboratories operating in Australia must meet
National Pathology Accreditation Advisory Council (NPAAC) standards
to be accredited. NPAAC standards look at required privacy and
confidentiality, treating patients with respect, risk management as
well as many other aspects.
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Environmental sustainability By minimising the generation of
waste, you can reduce the likelihood of contamination and accident.
You should carefully consider ways in which this can be achieved
prior to each process, routine or procedure.
Pipettes, burettes and volumetric flasks that are not
contaminated by biological waste should be rinsed with water
immediately after use to remove chemical residues. If you do not
rinse out the apparatus straight away, the traces of solution that
it still contains will dry out and the solute may stick to the
glass. This will make it much harder to clean properly later.
Any equipment contaminated with biological waste should be
properly treated to ensure all biological material is destroyed
before discarding. This may require autoclaving equipment or the
use of strong chemicals to ensure all microorganisms have been
destroyed.
Laboratory work creates waste and every effort should be made to
minimise this waste. Taking blood requires fresh sealed syringes
which can generate a deal of plastic waste, sharps waste and
biohazard waste. Disposable gloves will be replaced after each use
meaning this waste can build up quickly, making the need for
efficiency and not having to repeat procedures vital.
It is important to promote efficient waste management and
consumption of natural resources by the organisation for
environmental sustainability through the following actions:
• The minimisation of waste through implementation of a waste
management plan that utilises the waste management hierarchy
• The efficient and effective use of energy and other identified
resources (purchasing more efficient freezers and incubators)
• Seeking alternative sources of products so that we use
renewable resources where possible
• The efficient use of raw materials minimising waste
• The use of controls to minimise the risk of environmental
damage from the use and disposal of hazardous substances
• Efficient water use.
Major sustainability issues that every biological lab face
include:
• Energy consumption from fume hoods, freezers, incubators,
autoclaves and ovens
• Waste from single use sterile gloves, disposable gowns and
masks
• Hazardous chemicals from the strong cleaning products
• Biohazardous waste (bacteria, fungi and cell cultures).
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Bibliography
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Document revision Version Number
Details of the Revision Date Created / Approved
v1.0 Original issue 12/02/2020 JT / JS
v1.1 Legal and ethics edited to correct errors. 19/06/2020
JT
IntroductionProcess samples and associated request formsIdentify
specimens and request forms that do not comply with minimum
industry requirements for labelling, identification and test
requestsRecord any discrepancies and indicate what action is
requiredLog samples, recording details that allow accurate tracking
and chain of custodyStorage of samples
Perform testsSelect authorised tests indicated for the requested
investigationsCommon chemical pathology testsLiver function
testsBlood testsGlucose tolerance testDNA testingImmunological
tests
Conduct individual tests, or batches of tests, according to
documented methodologies, applying required quality control
proceduresManage tasks and organise work to ensure efficient use of
timeFlag test results that are outside accepted quality control
limitsBlank samples:Standards:Precision check samples:Test results
outside accepted quality control limitsStore unused sample for
possible future reference
Apply quality control processes to discriminate between
significant data and artefactConfirm with supervisor any further
testing requirementsRecord all test data, noting any phenomena that
may be relevant to the treatment of data or the interpretation of
results
Maintain laboratory recordsRecord entries on report forms or
into a laboratory information management system, accurately
calculating, recording or transcribing data as requiredAccurate
transcription of data
Ensure samples and associated paperwork maintain traceability
throughout testingLegal and ethical responsibilitiesEnvironmental
sustainability
BibliographyDocument revision