CHAPTER 25 DISORDERS OF RENAL FUNCTION Essentials of Pathophysiology.
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CHAPTER 25
DISORDERS OF RENAL FUNCTION
Essentials of Pathophysiology
PRE LECTURE QUIZ TRUE/FALSE
The kidneys do not begin to develop until the 12th week of gestation and start to function approximately 6 weeks later.
There is just a single theory that applies to kidney stone formation.
Most uncomplicated urinary tract infections (UTIs) are caused by Escherichia coli.
Upper urinary tract infections differ from those of lower urinary tract infections in that they incite an acute inflammatory response with marked systemic manifestations of infection.
Catheter-associated bacteriuria remains the most frequent cause of gram-negative septicemia in hospitalized patients.
F
F
T
T
T
PRE LECTURE QUIZ Autosomal dominant polycystic kidney disease
(ADPKD) is a systemic disorder that primarily affects the kidneys, resulting in the formation of fluid-filled __________ in both kidneys with the threat of progression to chronic renal failure.
____________ refers to urine-filled dilatation of the renal pelvis and calices associated with progressive atrophy of the kidney due to obstruction of the outflow of urine.
Most kidney stones are composed of __________. Nephrotic syndrome is associated with increased
glomerular permeability to the plasma __________, resulting in generalized edema.
The __________ phenomenon, the process by which the urine released from the bladder washes out the bacteria out of the urethra, aids in maintaining the sterility of the urine formed in the kidneys and found in the bladder.
calcium
Hydronephrosis
protein
sacs
washout
CYSTIC AND OBSTRUCTIVE DISORDERS
Cystic disease of the kidney Simple and acquired renal cysts Medullary cystic disease Autosomal dominant polycystic kidney
disease Obstructive disorders
Hydronephrosis Renal calculi
CONSEQUENCES OF DILATION OF RENAL TUBULES OR TRACT
Expansion of the kidney with urine (hydronephrosis) Increased pressure inside the renal
capsule Compartment syndrome compresses
blood vessels inside kidney Renal ischemia
Stasis of urine Risk of infection Stones
HYDRONEPHROSIS
QUESTION
Tell whether the following statement is true or false.
Hydronephrosis is categorized as a disorder of glomerular function.
ANSWER
FalseRationale: Hydronephrosis is caused by
a urinary obstruction, so it is considered an obstructive disorder. The glomerulus is not involved.
RENAL CALCULI
Saturation theory: urine is supersaturated with stone components
Matrix theory: organic materials act as a nidus for stone formation
Inhibitor theory: a deficiency of substances that inhibit stone formation
Four types of kidney stones:– Calcium stones (i.e., oxalate or phosphate)– Magnesium ammonium phosphate stones
– Uric acid stones – Cystine stones
URINARY TRACT INFECTIONS
Bacteria usually enter through the urethra
Host defenses include: Washout phenomenon Protective mucus Local immune responses and IgA Normal bacterial flora
SCENARIO:
Mr. K is paraplegic. When in the hospital, he had a catheter Now he has a high fever and complains
of joint and back pain He has pyuria and reports urgency BUN is 78 mg/dL (Normal 8-20 mg/dL) PCR is 4.7 mg/dL (Normal 0.6-1.2 mg/dL)Question: What complication are you most worried
about? Why?
QUESTION
Tell whether the following statement is true or false:
Urinary tract infections (UTIs) are usually caused by a virus.
ANSWER
FalseRationale: UTIs are most often caused
by bacteria that enter through the urethra (most common) or the bloodstream.
STRUCTURE OF THE GLOMERULUS
Glomerular capillaries and Bowman’s capsule are both made of epithelial cells sitting on a basement membrane
They are so tightly attached to each other that they share one basement membrane
The epithelial cells of Bowman’s capsule stand up from the basement membrane on foot processes, leaving pores between the feet for filtration
Blood in capillary
Urine
Basement membrane
Foot processes
Epithelial cell
IMMUNE DAMAGE TO THE GLOMERULUS
Circulating immune complexes lodge in glomerulus
Antibodies to glomerular proteins
GLOMERULAR DAMAGE
Proliferative: number of cells increase Sclerotic: amount of extracellular
matrix increases Membranous: thickness of glomerular
capillary wall increases All can decrease the efficiency of
filtration Allow blood cells, lipids, or proteins to
pass into the urine
DISORDERS OF GLOMERULAR FUNCTION
Nephritic syndromes Proliferative inflammatory response
Nephrotic syndrome Increased permeability of glomerulus
Mixed nephritic and nephrotic responses Chronic glomerulonephritis Glomerular lesions associated with
systemic disease
NEPHRITIC SYNDROMES
Proliferative inflammatory response RAA pathway activated; hypertension
Inflammatory process damages the capillary wall Red blood cells escape into the urine
Hematuria with red cell casts Hemodynamic changes decrease the GFR
Azotemia (presence of nitrogenous wastes in the blood), oliguria
NEPHROTIC SYNDROME
Other proteins lost in urine:Immunoglobulins and complement immune suppressionClotting and anticlotting proteins thrombosis Proteins that carry other blood components imbalances in blood components; altered drug dosages
QUESTION
Tell whether the following statement is true or false:
Nephritic syndromes are characterized by blood in the urine.
ANSWER
TrueNephritic syndromes decrease the
permeability of the glomerular capillary membrane, which results in hematuria, HTN, oliguria, and ↓ GFR.
SCENARIO:
A woman has diabetes mellitus She has severe edema and frothy,
cola-colored urine She has difficulty breathing, with
crackles in both lungs She just finished a course of
antibiotics for strep throat She is also taking corticosteroids for
lupus-related arthritisQuestion: What are three reasons for her renal
problems?
SCENARIO (CONT.)A woman has diabetes mellitus and
lupus and recently had strep throat. She has severe edema and frothy,
cola-colored urineQuestion: The doctor says the only way to
determine what has caused her glomerular disease is a renal biopsy. Why?
SCENARIO (CONT.) Urinalysis show that she is producing:
Urine with 500 mg protein/ day Contains blood and RBC casts High level of K+
Blood tests show: Hypoalbuminemia Slightly decreased K+
She has borderline hypertension
Question: Does she have nephritic syndrome or
nephrotic syndrome?
TUBULOINTERSTITIAL DISORDERS Acute tubular necrosis Pyelonephritis
Acute pyelonephritis Acute hypersensitivity to drugs Chronic pyelonephritis
Drug-related nephropathies
MALIGNANT TUMORS OF THE KIDNEY
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