Kidney Stones (Urolithiasis)

Result because there is secretion of some kind of material in the urine, which cannot be solubilized.

Occurrency of different types of stones:

Calcium oxalate (phosphate) = 75%

Struvite (Magnesium Ammonium Phosphate) = 15%.

The latter are mostly caused by infection with Proteus which, as you may recall, is urease + and splits urea into ammonia, raising the urine pH and facilitating the precipitation of magnesium ammonium phosphate salts.

Uric acid stones = 6%

Cystine ~4% or less

Stones can remain in the renal pelvis, where they are either asymptomatic or cause mild hematuria, or they can enter the ureter, where they can settle usually in one of three narrowed points—where the ureter enters the pelvis (uretopelvic junction), where it goes over the iliac vessels and, most commonly, where it enters the bladder (vesicouretaral junction). This impaction causes excruciating flank pain radiating into the groin and known as renal colic. Alternatively, the stone can make all the way into the bladder, where it can remain undetected, pass out of the urethra or obstruct bladder outflow causing bladder distention and, if untreated, leading to hydronephrosis.

Category: Nephrology Notes