IDIOPATHIC CALCIUM NEPHROLITHIASIS .1. DIFFERENCES IN URINE CRYSTALLOIDS, URINE SATURATION WITH BRUSHITE AND URINE INHIBITORS OF CALCIFICATION BETWEEN PERSONS WITH AND PERSONS WITHOUT RECURRENT KIDNEY STONE FORMATION

  • 1 January 1979
    • journal article
    • research article
    • Vol. 120  (6) , 658-+
Abstract
The propensity of urine to promote Ca stone formation was compared in 64 patients with recurrent idiopathic Ca nephrolithiasis and 30 healthy individuals without such a history. The rates of excretion of urine crystalloids, the urine saturation with brushite (CaHPO4.cntdot.2H2O), the ability of the urine to calcify collagen in vitro, and the concentration of urine inhibitors of collagen calcification were measured. The patients had a reduced urine citrate excretion rate in addition to an increased urine Ca excretion rate, while the rates for urine Mg, phosphate, uric acid and oxalate were not significantly different in the 2 groups of subjects. The urine concentration of Mg, phosphate and uric acid was decreased in the patients because of the higher urine volume. The urine creatinine excretion rate correlated with the rates of excretion of urine Ca, Mg, phosphate, uric acid and oxalate in both groups, which suggested that increased lean body mass, possibly associated with greater food intake, may be an important determinant of crystalloid excretion. The urine of the patients was significantly more saturated with brushite than the urine of the control subjects and resulted in greater collagen calcification when incubated in vitro. The urine concentration of inhibitors of collagen calcification was not significantly different in the 2 groups. The urine of patients with recurrent idiopathic Ca nephrolithiasis is more highly saturated with brushite, largely as a result of an increased urine Ca excretion rate, and contains a lower concentration of Mg and citrate, substances that tend to prevent the precipitation and growth of crystals in urine.