Chapter025

Chapter 25
Disorders of Renal Function
Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

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 Dilatation 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

Question
Tell whether the following statement is true or false:
Hydronephrosis is categorized as a disorder of glomerular
function.

Answer
False
Hydronephritis 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
• PCR is 4.7 mg/dL
Question:
• What complication are you most worried about? Why?

Question
UTIs are usually caused by a virus.

Answer
False
UTIs are most often caused by bacteria that enter through
the urethra (most common) or the bloodstream.

• 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

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
suppression
Clotting and anticlotting
proteins  thrombosis
Proteins that carry other
blood components 
imbalances in blood
components; altered drug
dosages

Question
Nephritic syndromes are characterized by blood in the
urine.

Answer
True
Nephritic 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
arthritis
Question:
• 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
urine
Question:
• 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

Chapter025

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