Renal Pathology 7: Urolithiasis (Dobson)

Question 1

Bilateral partial obstruction

Answer 1

inability to concentrate urine (hyposthenuria); some patients develop distal tubular acidosis, and HTN is common

Question 2

Bilateral complete obstruction

Answer 2

rapid onset of oliguria/anuria and is incompatible with survival unless obstruction is relieved; after relief post obstructive diuresis occurs (can be massive)

Question 3

Unilateral complete or partial obstruction

Answer 3

may remain silent; unaffected kidney can maintain adequate renal function

Question 4

Most important determinant of initiation and propagation of stones?

Answer 4

increased urinary concentration of the stones constituents that exceeds their solubility (supersaturation)

Question 5

Magnesium ammonium phosphate stones

Answer 5

largely after infections by urea-splitting bacteria (Proteus, Pseudomonas, Klebsiella) that convert urea to ammonia; “staghorn calculi” occupying large portions of the renal pelvis

Question 6

“staghorn calculi”

Answer 6

Magnesium ammonium phosphate stones; occupy large portions of the renal pelvis

Question 7

Clinical features of urolithiasis

Answer 7

may be asymptomatic, produce severe renal colic and abdominal pain; may cause significant renal damage; and pt may present w hematuria

Question 8

Answer 8

Magnesium ammonium phosphate stones; occupy large portions of the renal pelvis

Question 9

Most common type of stone

Answer 9

Calcium oxalate stones; secretes too much calcium in renal tubules; can be a result of hyperparathyroidism

Question 10

Hypocitraturia

Answer 10

seen in diarrhea and metabolic acidosis; may lead to calcium stones; due to volume depletion; acidemia causes hypocitraturia - less citric acid which binds calcium)

Question 11

Struvite stones

Answer 11

made of magnesium ammonium phosphate; forms the largest kidney stones; caused by infection; large stones that occupy renal pelvis; do not pass stay in pelvis; cause obstruction, leads to hydronephrosis

Question 12

Cystine Stones

Answer 12

formed with genetic diseases (cystinuria) affecting PCT; prevent reabsorption of proteins in the urine; forms at low acidic urinary pH; if you see kid presenting with renal stone; are radiolucent

Question 13

All renal stones form due to what?

Answer 13

supersaturation

Question 14

What is cornerstone of treatment with renal stones

Answer 14

adequate hydration; all you need to do is drink more water

Question 15

Pure vegan diets

Answer 15

can cause calcium oxalate stones because foods are rich in oxalate

Question 16

calcium phosphate stones

Answer 16

most common renal stones found in children; usually presents with elevated urine pH (alkaline) - pHosphate

Question 17

Elongated wedge shape on microscopy

Answer 17

calcium pHosphate crystals

Question 18

“envelope” on microscopy

Answer 18

calcium oxalate crystals

Question 19

MAP stones almost always occur in concurrent with what?

Answer 19

during UTI with urease positive organism (urea into ammonium and CO2) Proteus, Staph and Klebsiella; 3 times more common in women

Question 20

“coffin lid” or rectangular prism shape on microscopy

Answer 20

Magnesium ammonium phosphate stones

Question 21

Uric acid stones

Answer 21

Gout causes hyperuricemia and can lead to uric acid stones; conditions with rapid cell turnover like leukemia and lymphoma can cause hyperuricemia; also tumor lysis syndrome

Question 22

Conditions like leukemia and lymphoma can cause what type of stone?

Answer 22

Uric acid stones; because of high cell turnover; allopurinol is go to treatment

Question 23

Tumor lysis syndrome causes what kind of stones?

Answer 23

uric acid stones

Question 24

Patients with uric stones usually excrete what type of urine?

Answer 24

Acidic urine

Question 25

Sodium cyanide-nitroprusside urine test

Answer 25

used to test for cystinuria which forms cystine stones; turns red-purple color