Renal Pathology 7: Urolithiasis (Dobson) Flashcards
Bilateral partial obstruction
inability to concentrate urine (hyposthenuria); some patients develop distal tubular acidosis, and HTN is common
Bilateral complete obstruction
rapid onset of oliguria/anuria and is incompatible with survival unless obstruction is relieved; after relief post obstructive diuresis occurs (can be massive)
Unilateral complete or partial obstruction
may remain silent; unaffected kidney can maintain adequate renal function
Most important determinant of initiation and propagation of stones?
increased urinary concentration of the stones constituents that exceeds their solubility (supersaturation)
Magnesium ammonium phosphate stones
largely after infections by urea-splitting bacteria (Proteus, Pseudomonas, Klebsiella) that convert urea to ammonia; “staghorn calculi” occupying large portions of the renal pelvis
“staghorn calculi”
Magnesium ammonium phosphate stones; occupy large portions of the renal pelvis
Clinical features of urolithiasis
may be asymptomatic, produce severe renal colic and abdominal pain; may cause significant renal damage; and pt may present w hematuria
Magnesium ammonium phosphate stones; occupy large portions of the renal pelvis
Most common type of stone
Calcium oxalate stones; secretes too much calcium in renal tubules; can be a result of hyperparathyroidism
Hypocitraturia
seen in diarrhea and metabolic acidosis; may lead to calcium stones; due to volume depletion; acidemia causes hypocitraturia - less citric acid which binds calcium)
Struvite stones
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
Cystine Stones
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
All renal stones form due to what?
supersaturation
What is cornerstone of treatment with renal stones
adequate hydration; all you need to do is drink more water
Pure vegan diets
can cause calcium oxalate stones because foods are rich in oxalate
calcium phosphate stones
most common renal stones found in children; usually presents with elevated urine pH (alkaline) - pHosphate
Elongated wedge shape on microscopy
calcium pHosphate crystals
“envelope” on microscopy
calcium oxalate crystals
MAP stones almost always occur in concurrent with what?
during UTI with urease positive organism (urea into ammonium and CO2) Proteus, Staph and Klebsiella; 3 times more common in women
“coffin lid” or rectangular prism shape on microscopy
Magnesium ammonium phosphate stones
Uric acid stones
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
Conditions like leukemia and lymphoma can cause what type of stone?
Uric acid stones; because of high cell turnover; allopurinol is go to treatment
Tumor lysis syndrome causes what kind of stones?
uric acid stones
Patients with uric stones usually excrete what type of urine?
Acidic urine
Sodium cyanide-nitroprusside urine test
used to test for cystinuria which forms cystine stones; turns red-purple color
