Bone mineral content and mineral metabolism during cyclosporine treatment of nephrotic Syndrome.

Abstract

Although cyclosporine (Cy) has been associated with bone loss following transplantation, its effects on bone in growing children are largely unknown. Thirty-seven patients (2-16 years of age) with remitting nephrotic syndrome (NS), n = 16 receiving Cy for 39 +/- 27 months and n = 21 without Cy, underwent mineral metabolism and bone turnover assessment. In 28 of 37 patients, bone mineral density (BMD) was obtained while off corticosteroid therapy (Rx). Urinary calcium (Ca), phosphate (PO(4)), and magnesium (Mg) excretion was normal, but serum Mg was lower in patients receiving Cy (1.8 +/- 0.1 v 1.95 +/- 0.2 mg/dL, P < .05). BMD Z scores were similar at the spine (-0.45 +/- 0.74 v 0.04 +/- 0.9) and femur (-0.17 +/- 0.52 v 0.38 +/- 1.28) with no Z score <-2. Serum bone-specific alkaline phosphatase was normal, and N-telopeptide of type I collagen also normal, was higher on Cy (P < .05). Cumulative prednisone exposure was similar and had no significant effect on height and BMD Z scores. Length of Cy-Rx and time elapsed from onset of NS did not correlate with BMD, height Z score, or markers of bone turnover. In growing children with NS, during long-term Cy-Rx urinary wasting of Ca and Mg was absent and bone density was preserved.