Chapter 24
Disorders of Renal Function
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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
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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
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Hydronephrosis
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Question
Tell whether the following statement is true or false.
Hydronephrosis is categorized as a disorder of glomerular
function.
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Answer
False
Rationale: Hydronephrosis is caused by a urinary
obstruction, so it is considered an obstructive disorder.
The glomerulus is not involved.
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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
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Urinary Tract Infections
• Bacteria usually enter through the urethra
• Host defenses include:
– Washout phenomenon
– Protective mucus
– Local immune responses and IgA
– Normal bacterial flora
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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
• PCR is 4.7 mg/dL
Question:
• What complication are you most worried about? Why?
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Question
Tell whether the following statement is true or false:
Urinary tract infections (UTIs) are usually caused by a
virus.
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Answer
False
Rationale: UTIs are most often caused by bacteria that
enter through the urethra (most common) or the
bloodstream.
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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
Urine
Epithelial
cell
Foot processes
Basement membrane
Blood in
capillary
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Immune Damage to the Glomerulus
Antibodies to glomerular
proteins
Circulating immune complexes
lodge in glomerulus
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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
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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
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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
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Nephrotic Syndrome
• Other proteins lost in
urine:
Immunoglobulins and
complement  immune
suppression
Clotting and anticlotting
proteins  thrombosis
Proteins that carry other
blood components 
imbalances in blood
components; altered
drug dosages
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Question
Tell whether the following statement is true or false:
Nephritic syndromes are characterized by blood in the
urine.
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Answer
True
Nephritic syndromes decrease the permeability of the
glomerular capillary membrane, which results in
hematuria, HTN, oliguria, and ↓ GFR.
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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
arthritis
Question:
• What are three reasons for her renal problems?
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Scenario (cont.)
A woman has diabetes mellitus and lupus and
recently had strep throat.
• She has severe edema and frothy, colacolored urine
Question:
• The doctor says the only way to determine
what has caused her glomerular disease is a
renal biopsy. Why?
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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?
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Tubulointerstitial Disorders
• Acute tubular necrosis
• Pyelonephritis
– Acute pyelonephritis
– Acute hypersensitivity to drugs
– Chronic pyelonephritis
• Drug-related nephropathies
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