[Predictive value of lithogenic risk in hypercalciuria: should 24-hour urine calcium be measured?]

Three studies have been undertaken to evaluate the predictive value for new stone formation of urinary calcium excretion. In study 1, 24-hr calciuria was similar in 52 patients with benign stone disease (less than 3 new stones or 1 staghorn calculus in the 5 preceeding years) and in 46 patients with severe lithiasis (more than 3 stones or 1 staghorn calculus), based on a retrospective assessment of stone disease evolution. In study 2, urinary fasting Ca/Creat was identical in 43 non-hyperparathyroid stone formers (including 31 with severe lithiasis) and in 35 patients with proven or suspected primary hyperparathyroidism (including 19 with benign lithiasis, 8 with severe lithiasis and 8 with no stone). In study 3, stone recurrence, assessed prospectively, felt significantly in patients given a high fluid intake alone or associated with 50 mg/d of hydrochlorothiazide, independently of urinary calcium excretion. Urinary calcium determination therefore appears useless for stone recurrence prediction.