Persistence of Diminished Bone Mineral Content Following Renal Transplantation in Childhood

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Abstract
Bone mineral content (BMC) was measured in the nondominant arm of 18 children (aged 3 7/12 to 17.5 yr) for a total 783 mo. after renal transplantation. Using photon absorptiometry, 89 measurements were made; 17 of the 18 patients had a functioning graft and 1 patient died. Significant demineralization, a BMC greater than -2 SD below appropriate control volumes, was found in 11 of 18 patients (62%) and 55 of 89 measurements (61%). Bone loss was progressive; among the 16 patients followed for more than 6 mo., 10 showed a decline of more than 0.5 SD in BMC, 5 had no change and only 1 showed improvement. No relationship was found between BMC and the use of furosemide, type of transplant (15 living, 7 cadaver), prior renal disease (6 with glomerulonephritis, 11 tubulointerstitial), need for a 2nd graft (5 patients), chronic anticonvulsant therapy, or serum Ca and phosphate values. BMC was slightly correlated (P < 0.05) with alkaline phosphatase values. BMC was more strongly correlated with serum creatinine (y = -0.48x + 1.25, r = -0.042, P < 0.001) and prednisone dose (mg/kg per day) (y = -0.65x + 0.481, r = - 0.543, P < 0.001) in an inverse relationship. Patients whose serum creatinine value was less than 1 mg/dl had a BMC of -0.71 .+-. 0.34 SD; those with serum creatinine value greater than 2 mg/dl had BMC of -3.32 .+-. 0.31 SD, different at P < 0.001. Patients receiving daily prednisone therapy had a significantly lower BMC than those receiving alternate-day therapy (-3.11 .+-. 1.23 SD vs. -1.72 .+-. 1.29 SD, P < 0.005). Although overt avascular necrosis developed in only 3 patients, prolonged and progressive bone demineralization appears to be a problem following transplantation in children. This bone mineral loss is related to reduced renal function and the administration of glucocorticoids and indicates that these patients may possibly be at risk for disabling bone disease.