CHAPTER 25 DISORDERS OF RENAL FUNCTION Essentials of Pathophysiology.

 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