DIETARY HYPERCALCIURIA IN PATIENTS WITH CALCIUM-OXALATE KIDNEY-STONES

The relative importance of dietary factors in causing hypercalciuria w as assessed in 282 unselected patients with calcium oxalate kidney sto nes. The 124 patients found to be hypercalciuric on either their custo mary free diet or on a 25-mmol (1000-mg) calcium defined diet (or both ), were classified according to their pattern of calcium excretion on the two diets. Unexpectedly, about half of the patients who were hyper calciuric on their free diet exhibited a calcium excretion that fell m arkedly or normalized on the high-calcium defined diet. These patients were defined as having dietary hypercalciuria. For all 282 patients, multiple-regression analysis suggested that dietary sodium was at leas t as important as was dietary calcium, and more important than dietary protein, carbohydrate, phosphorus, purine, or oxalate, in contributin g to calcium excretion on the free diet. Among the 124 hypercalciuric patients, urinary calcium excretion increased by 0.0193 mmol (0.77 mg) per mmol sodium excretion. Dietary habits, particularly a high sodium intake, may commonly contribute to hypercalciuria in patients with ca lcium oxalate stones.