1. Chapter 24 Disorders of Renal Function

2. 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

3. 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

4. Hydronephrosis

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

6. Answer
False
Rationale: Hydronephrosis is caused by a urinary obstruction, so it is considered an obstructive disorder. The glomerulus is not involved.

7. 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

8. Urinary Tract Infections
Bacteria usually enter through the urethra
Host defenses include:
Washout phenomenon
Protective mucus
Local immune responses and IgA
Normal bacterial flora

9. 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?

10. Question Tell whether the following statement is true or false:
Urinary tract infections (UTIs) are usually caused by a virus.

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

12. 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

13. Immune Damage to the Glomerulus
Antibodies to glomerular proteins
Circulating immune complexes lodge in glomerulus

14. 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

15. 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

16. 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

17. 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

18. Question Tell whether the following statement is true or false:
Nephritic syndromes are characterized by blood in the urine.

19. Answer
True
Nephritic syndromes decrease the permeability of the glomerular capillary membrane, which results in hematuria, HTN, oliguria, and ↓ GFR.

20. Scenario: She has severe edema and frothy, cola-colored urine
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?

21. 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?

22. 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?

23. Tubulointerstitial Disorders
Acute tubular necrosis
Pyelonephritis
Acute pyelonephritis
Acute hypersensitivity to drugs
Chronic pyelonephritis
Drug-related nephropathies