Calcium and vitamin-D metabolism in nephrotic syndrome.

A child with long-standing steroid resistant minimal-change nephrotic syndrome developed mild muscular weakness. Laboratory studies demonstrated reduction in both protein-bound and ionized calcium concentrations which were accompanied by high serum PTH and low urinary calcium excretion. These findings were related to the marked sustained reduction in the serum concentrations of 25-hydroxyvitamin-D3 and 1,25-dihydroxyvitamin-D3. Relief of the muscular weakness and normalization of serum ionized calcium and PTH were realized with oral administration of 1,25-dihydroxyvitamin-D3 at 0.25 mcg per day. These beneficial effects persisted for over one year of follow-up.