CLS 500 Application and Interpretation of Clinical Laboratory Data Routine Urinalysis- Physical and Chemical Examination of Urine 1 Routine Urinalysis- Physical and Chemical Examination fUi University of Nebraska Medical Center of Urine CLS 500: Application and Interpretation of Clinical Laboratory Data Objectives: On completion of this unit, participants will be able to: • Describe considerations on collection, handling, and processing of urine specimens • Identify screening tests for physical and Identify screening tests for physical and chemical examination of urine • Describe major sources of error in routine urinalysis procedures • Define common terms applied to urinalysis and renal disease 2 Objectives (continued) • Correlate physical & chemical tests of urine in: – Cystitis – Pyelonephritis – Renal glycosuria – Diabetes mellitus – Diabetes insipidus – Hepatic, obstructive or hemolytic jaundice – Acute and chronic glomerulonephritis – Nephrotic syndrome 3 Objectives (continued) • Explain the significance of the following: – Pos Clinitest and neg dipstick for glucose – Pos dipstick for glucose and neg Clinitest – False positive dipstick for protein – False negative for ketones – False negative for bilirubin – Neg bilirubin dipstick and pos Ictotest – Pos bilirubin and neg urobilinogen – Neg bilirubin and pos urobilinogen 4 Objectives (continued) • Predict the potential changes that may take place in a urine specimen that remains at room temperature for longer than 2 hours 5 What is Urine? • A fluid which is continuously formed in and excreted from the body • Composed of water and metabolic waste products metabolic waste products • An actual fluid biopsy of the kidney – kidney is the only organ with such a noninvasive means by which to evaluate its status 6
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CLS 500 Application and Interpretation of Clinical Laboratory DataRoutine Urinalysis- Physical and Chemical Examination of Urine 1
Routine Urinalysis- Physical and Chemical Examination
f U i
University of Nebraska Medical Center
of Urine
CLS 500: Application and Interpretation of Clinical Laboratory Data
Objectives: On completion of this unit, participants will be able to:
• Describe considerations on collection, handling, and processing of urine specimens
• Identify screening tests for physical andIdentify screening tests for physical and chemical examination of urine
• Describe major sources of error in routine urinalysis procedures
• Define common terms applied to urinalysis and renal disease 2
Objectives (continued)• Correlate physical & chemical tests of
urine in:– Cystitis
– Pyelonephritis
– Renal glycosuria
– Diabetes mellitus
– Diabetes insipidus
– Hepatic, obstructive or hemolytic jaundice
– Acute and chronic glomerulonephritis
– Nephrotic syndrome3
Objectives (continued)
• Explain the significance of the following:– Pos Clinitest and neg dipstick for glucose– Pos dipstick for glucose and neg Clinitest– False positive dipstick for proteinp p p– False negative for ketones– False negative for bilirubin– Neg bilirubin dipstick and pos Ictotest– Pos bilirubin and neg urobilinogen– Neg bilirubin and pos urobilinogen
4
Objectives (continued)
• Predict the potential changes that may take place in a urine specimen that remains at room temperature for longer than 2 hours
5
What is Urine?• A fluid which is continuously formed
in and excreted from the body
• Composed of water and
metabolic waste productsmetabolic waste products
• An actual fluid biopsy of the kidney– kidney is the only organ with such a noninvasive means
by which to evaluate its status
6
CLS 500 Application and Interpretation of Clinical Laboratory DataRoutine Urinalysis- Physical and Chemical Examination of Urine 2
Functions of the Kidney
• Produces urine
• Maintains electrolyte balance
• Maintains blood pH
• Produces hormones
• Excretes waste
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The Purpose of Urinalysis?
• To aid in the diagnosis of disease
• To monitor wellness (screening for asymptomatic, congenital, or hereditary disease))
• To monitor the progress of disease
• To monitor therapy (effectiveness or complications)
A Complete Urinalysis Providesa Fountain of Information
pancreas muscle
intoxication
acid base equilibrium inborn errors of metabolismwater status
• Chemical reaction causes the color of the pad to
change: reaction is timed
• Color compared to a color chart for interpretation
Reagent Strip Proper Storage
• Tightly closed container
• Cool dry place
• Avoid volatile fumes
• Expiration date
• Do not use if pads are discolored
• Do not touch pads
• Run positive and negative controls once/day30
CLS 500 Application and Interpretation of Clinical Laboratory DataRoutine Urinalysis- Physical and Chemical Examination of Urine 6
Quality Control• Ensures reliability of results
• Evaluates reagent strip
• Run 2 controls once a day
• Positive control
N ti t l
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• Negative control
• BOTH controls MUST be ‘ok’ else patient testing cannot be performed
The Dipstick Procedure
• Wear gown & gloves
• Mix the urine
• Insert reagent stripg p
• Remove excess urine
• Time the reactions
• Compare test areas to color chart
• Record results
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The Urine Dipstick10 Reactions on 1 Plastic Strip
• Glucose• Bilirubin• Ketones• Specific gravity
• Purpose of the test
• What is normal
• What is abnormal• Specific gravity• Blood• pH• Protein• Urobilinogen• Nitrites• Leukocytes
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• Causes of abnormal results
• Causes of false pos/neg results
Glucose
• All glucose is normally reabsorbed in the tubules unless the blood level is higher than the renalunless the blood level is higher than the renal threshold (160 to 180 mg/dl)
• Normal = Negative
• Abnormal = Diabetes mellitusImpaired tubular reabsorptionInborn errors of metabolism
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Glucose
• Glucosuria
Glycosuria
• Caused by renal and non renal disease
Terms used interchangeably
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• Caused by renal and non-renal disease– Pre-renal glycosuria: plasma glucose level
exceeds renal threshold (diabetes mellitus)
– Renal glycosuria: plasma glucose level below renal threshold, but tubules cannot reabsorb glucose back into bloodstream
• The protein that is found in urine comes from– Bloodstream– Urinary tract
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• Proteinuria is an indicator of early renal disease
• Proteinuria also caused by non-renal disease– Multiple myeloma
Renal Causes of Proteinuria
• Glomerular damage:– Most serious cause of proteinuria– Most common cause of proteinuria– Glomerulonephritis
N h ti S d (hi h t l l f t i )
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– Nephrotic Syndrome (highest levels of protein)
• Tubular dysfunction:– Reabsorption capability decreased– Toxin exposure, inherited disorder– Fanconi’s syndrome: heavy metal poisoning
Protein• Sensitivity: ~ 10-25 mg/dl
• Specificity: reacts primarily with albumin
• False Positive• False Positive– Highly buffered or alkaline urine >8.0– Alkaline drugs– Improper storage and handling– Contamination of detergents
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Protein• False Negative
– Dilute urine
– Presence of other proteins• Uromodulin (Tamm-Horsfall protein matrix in casts)
• Globulins
M l bi• Myoglobin
• Free light chains (Bence-Jones protein)
• Hemoglobin
– Exercise/transitory conditions
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CLS 500 Application and Interpretation of Clinical Laboratory DataRoutine Urinalysis- Physical and Chemical Examination of Urine 11
Urobilinogen
• Urobilinogen is formed in the intestine from bili bi b b t i ( t i t d i th f )bilirubin by bacteria (most is excreted in the feces) but some is reabsorbed back into the bloodstream where small amounts are excreted in the urine
• Normal = 0.2 to 1.0 mg/dl
• Abnormal = Hemolytic disease
Liver disease
Cannot determine absence of UBG 61 62
Nitrites
• Some gram negative bacteria reduce dietary nitrates to nitrites. The bacteria that cause urinary tract infections (UTI) are often nitrite producersinfections (UTI) are often nitrite producers
• Normal = Negative
• Abnormal = UTI
Cystitis (bladder infection)
Pyelonephritis (kidney infection)
Rapid screening test for UTI 63
Nitrite• False Positive
– Substances that mask reaction color
– Foods (beets); Drugs
– Improper specimen storage/handling
F l N ti• False Negative– Ascorbic acid– Bacteria cannot reduce nitrates– Bladder time not sufficient: need 4 hours– Low nitrate levels (lacks dietary nitrates)– Antibiotic inhibition of bacteria– Further reduction of nitrites to nitrogen
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Leukocytes
• The presence of leukocytes in the urine indicate a possible urinary tract infection Can detect intactpossible urinary tract infection. Can detect intact WBC and lysed WBC (granulocytes)