Ammonium urate urolithiasis in the rat with portocaval shunt--some aspects of mineral metabolism and urine composition.

In the male rat the effects of portocaval shunt (PCS) on mineral metabolism (fractional intestinal absorption, minerals in serum, in bone, in kidney, and in urine) and the effects on urinary constituents were studied. PCS induced a degree of hyperparathyroidism and the formation of ammonium acid urate urinary tract stones. These phenomena were associated with elevated uric acid, ammonium, urinary pH, as well as with elevated supersaturation of urine with struvite, and to a lesser degree with ammonium acid urate. It is suggested that in the rat PCS interferes with both parathyroid gland function and urinary nucleation of ammonium acid urate.