Chapter 13 - Kidney and Its Collecting System

Question 1

Glomerular Diseases

Answer 1

Most are due to immune mechanisms
Circulating immune complexes deposited in the glomerulus (inflammation via type 3 hypersensitivity rxn) complement activation [in situ immune complexes (inflammation via type 3 hypersensitivity rxn)

Podocyte (foot process) injury

Question 2

Nephrotic Syndrome

Answer 2

Massive proteinuria (3.5 g+ a day)
Hypoalbuminemia (generalized edema [anasarca] due to hypoalbuminemia)
Hyperlipidemia and lipiduria (cause unclear), Usually minimal renal failure unless very severe

Question 3

Minimal Change Disease

Answer 3

In preadolescents, inimal-change nephrotic syndrome - 85-95% of all cases of nephrotic syndrome
Adults, 10-15% of primary nephrotic syndrome cases
So-named b/c glomeruli appear normal by light microscopy
Not immune-complex damage
90% response to steroids in children, but recurrence high
Adults less responsive

Question 4

Nephritic Syndrome

Answer 4

Seen w/ immune complex glomerular injury associated w/ non-renal disease or occurring w/ primary renal disease

Severe injury to glomerular capillaries allowing RBCs and protein to pass through
Hematuria, Oliguria, Azotemia, Hypertension

Question 5

Acute proliferative Postinfectious (Poststreptococcal) Glomerulonephritis

Answer 5

Not clear whether immune complexes are circulating or in situ, Activation of complement pathway incites inflammatory response
1-4 weeks following pharyngeal or skin infection w/ certain strains of beta hemolytic group A streptococci
Most children recover w/ minimal residual damage

Question 6

IgA Nephropathy

Answer 6

Characterized by presence of prominent IgA deposits in the mesangial region
Recurrent hematuria (most common type of glomerulonephritis worldwise)

Affects children and young adults, one of most common causes of recurrent microscopic or gross hematuria

Berger Disease (children like burgers)

Question 7

Glomerular lesions associated with systemic diseases

Answer 7

Membranous nephritis, Cresentic glomerulonephritis (Lupus Nephritis), Nodular glomerulosclerosis (Diabetes mellitus)

Question 8

Membranous nephritis

Answer 8

Autoantibodies cross-reacting w/ podocyte antigens, damage probably due to membbrane attack complex injury, results in nephrotic syndrome

Question 9

Cresentic glomerulonephritis

Answer 9

When associated w/ SLE “Lupus Nephritis”, Immune complex mediated, severe glomerular injury, nephritic syndrome, “Wireloop” glomerular changes

Question 10

Urinary Tract Infection

Answer 10

Urine normally sterile, Bacteria in “clean catch” or catheterized urine implies infection in bladder (cystitis) or kidney (pyelonephritis)
One of the commonest infections in general population
:Ascending” infections from urethral contamination by “coliform” organisms, especially E. coli
Symptoms of cystitis (suprapubic pain, pain on urination, frequent urination, blood in urine)
Symptoms of pyelonephritis (flank pain, fever, infection may be silent)

Question 11

Acute Renal Failure

Answer 11

Abrupt onset, reduced urinary flow, rising serum urea nitrogen and creatinine, electrolyte imbalance (especially inc potassium and sodium retention), metabolic acidosis, *Peripheral edema, pulmonary edema, pleural and pericardial effusions

Question 12

Acute Renal Failure - Pre-renal

Answer 12

Before blood reaches kidney
Severe circulating blood volume loss, trauma w/ massive hemorrhage, low cardiac output (following acute myocardial infarction or chronic heart failure)

Question 13

Acute Renal Failure - Renal

Answer 13

Wrong w/ kidney
Acute tubular necrosis
Destruction of epithelium of tubules resulting in loss of renal function
*Most common cause of acute renal failure
Ischemic type (hypotension, myoglobinuria, Hemolytic crises)
Nephrotoxic (mercury, carbon tetracholoride, radiographic contrast)

Question 14

Acute Renal Failure - Post-Renal

Answer 14

Obstruction to outflow of urine

obstruction by ureteral or bladder tumor, obstruction of prostatic urethra by enlarged prostate

Question 15

Chronic Renal Failure

Answer 15

Glomerulonephritis - 30%, Diabetes Mellitus - 20%, Vascular diseases including hypertension - 15%, Polycystic disease of kidney - 10%, Remainder - 25%
Symptoms: same as acute renal failure, but much slower onset, often over years
Dental Issues: drug-related (immunosuppression and gingival hyperplasia), generally poor dental care

Question 16

Hemolytic-Uremic Syndrome

Answer 16

75% due to Shiga toxin-producing E. coli O157:H7 and Shigella dysenteriae
Damages endothelial cells of glomerular capillaries resulting in intracapillary fibrin thrombi
RBCs hemolyzed as they pass through affected capillaries

Question 17

Benign Arterionephrosclerosis

Answer 17

Strongly associated w/ hypertension
Hypertension may directly damage kidney, caused by damage to kidney which then elevates BP by renin-angiotensin system activation benign as opposed to malignant

Question 18

Malignant Arterionephrosclerosis

Answer 18

Malignant refers to aggressive and formerly fatal outcome, not to neoplastic change
Very high blood pressures not very responsive to therapy
Rare, but may follow long-standing benign nephrosclerosis, injury to arterioles and small arteries

Question 19

Polycystic Kidney Disease

Answer 19

Adult form: AD, Bilateral, Kidney parenchyma replaced by cysts leading to renal failure, most common genetic cause of renal failure

Neonatal form: AR, often die during perinatal or neonatal period of renal or hepatic failure, cysts of liver occur as well

Question 20

Urinary Calculi (Stones)

Answer 20

Form in renal pelvis or calyces, usually 2-3 mm; massive ones called “staghorn” calculi due to shape, pain results when stones pass into ureter inducing spasm “ureteral colic”
Most are composed of calcium oxalate or calcium oxalate/calcium phosphate
Ureterolithiasis: stones lodging in the ureter passing in a slow and painful manner
Causes: idopathic (absorptive) hypercalciuria: 50%, excessive calcium absorption from GI tract, Urinary stasis, chronic infections and foreign objects

Question 21

Hydronephrosis

Answer 21

Dilation of renal pelvis and calyces due to outflow obstruction anywhere from the renal pelvis to the urethra
Causes: calculi, tumors, inflammation, spinal cord damage resulting in a “neurogenic bladder” and failure to empty

Question 22

Renal Cell Carcinoma

Answer 22

Arises from tubular epithelium, 85-90% of kidney tumors, often has a “clear cell” pattern microscopically - “clear cell carcinoma”, most common type
Risk inc in: smokers, men, obese and hypertensive individuals

Question 23

Transitional Cell Carcinoma

Answer 23

Arises from urothelium of renal pelvis, urinary bladder, ureters and urethra
Associated w/ beta naphthylamine industrial exposure (cancers occur about 20 yrs later)
Smoking increases risk 2-4X
Bladder infection by the parasite schistosoma also related to cancer

Question 24

Wilm’s Tumor (Nephroblastoma)

Answer 24

One of the commonest, intra-abdominal malignant neoplasms of childhood (most in ages 1-4)
Very aggressive if untreated
Modern treatments have increased survival dramatically