[Value of the measurement of urinary calcium in calcium lithiasis].

The author reports certain data from the literature and based upon his own experience. The urinary excretion of calcium is dependent upon diet and in particular sodium intake. Urinary calcium decreases when sodium intake is reduced. The administration of rapidly absorbed sugars and protein rich diets cause an increase in urinary calcium. It is thus of fundamental importance to be aware of the nature of the diet in patients in whom 24 hour urinary calcium is measured. In particular, such measurements are of no value during the immediate postoperative period. Is the existence of hypercalciuria (defined by a urinary calcium greater than 0.1 mmol/kg/day) truly responsible for an increase in the frequency of recurrences of lithiasis? In two groups of patients, one with progressive lithiasis and the other with non-progressive lithiasis, the mean urinary calcium for each of the two groups was the same. In addition, patients with a high daily calcium excretion were not necessarily those with progressive lithiasis. Three groups of patients were also compared, according to whether they had a high fluid intake, a fluid intake associated with a hydrochlorothiazide or a fluid intake associated with a neutral phosphorus salt. Phosphate therapy was a failure. In comparison with their previous state, patients receiving merely a high fluid intake or in combination with thiazides had less recurrences than before such treatment. The group treated with thiazides had significantly less recurrences than the group treated by simple high fluid intake. However urinary calcium was not lowered by thiazides. Thus the role of thiazides probably does not lie in hypocalciuria but merely in an increase in urine output.