The effects of the calcium-restricted diet of urolithiasis patients with absorptive hypercalciuria type II on risk factors for kidney stones and osteopenia.

The calcium (Ca)-restricted diet of urolithiasis patients with absorptive hypercalciuria type II may decrease Ca excretion but increase biochemical markers of risk for osteopenia. We randomly allocated 25 patients from six hospitals into an experimental group (Ca restriction to 500 mg/day, oxalate-rich products discouraged and normalization of animal protein and sodium) and a control group (no restrictions) for one month. The urinary Ca excretion did not decrease significantly, but the oxalate excretion decreased, although not significantly. The hydroxyproline:creatinine ratio in fasting urine seemed to increase and the calcium:creatinine ratio to decrease. The deoxypyridinoline:creatinine ratio in fasting urine did not change. We conclude that our Ca-restricted diet, which is lower in Ca, animal protein and table salt due to the omission of dairy products, may be of benefit for absorptive hypercalciuria type II patients without enhancing the risk for osteopenia. However, a long-term clinical trial is required.