Nephrocalcinosis in three siblings with idiopathic hypercalciuria

Idiopathic hypercalciuria (IH) associated with nephrocalcinosis was found in three of six siblings. After the three affected children were maintained on a low-calcium diet, they demonstrated increasing hypercalciuria, parathyroid hormone, and vitamin D-3 levels. An oral calcium loading test was not necessary to diagnose renal IH. During treatment with hydrochlorothiazide, the calcium excretion was normalized. These patients are remarkable because nephrocalcinosis is generally regarded as a rare complication of renal M. Moreover, the fact that three of six siblings are affected raises the question of whether the renal form of IH is genetically distinct from other forms of IH.