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 (PO₄), 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.