Renal Osteodystrophy After Successful Renal Transplantation: A Histomorphometric Analysis in 57 Patients

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Renal transplantation is the treatment of choice for patients with end-stage renal disease. It corrects most of the metabolic abnormalities that cause renal osteodystrophy. Nevertheless, renal osteodystrophy persists in many transplant recipients. The aim of this study was to investigate frequency and histomorphometric pattern of bone disease after renal transplantation. Bone biopsy specimens were taken from the iliac crest of 57 patients, including 28 women (26–70 years old) and 29 men (27–67 years old). Indications for biopsy were hypercalcemia, elevation of parathyroid hormone, and, in 19 cases, without suspected bone abnormalities based on laboratory parameters. The mean time of dialysis prior to renal transplantation was 43 months (range, 6–91 months in women and 10–111 months in men) and the mean interval between transplantation and bone biopsy was 53.5 months (range, 4–191 months in women and 5–90 months in men). Fourteen patients were treated with either 25-hydroxyvitamin D 3 and/or 1-α hydroxyvitamin D 3 or 1,25 dihydroxyvitamin D 3, 3 with phosphate-binding agents. The immunosuppression consisted of cyclosporine, azathioprine, and prednisolone. The cumulative dosage of corticosteroids was 5569 ± 5305 mg. For static and dynamic histomorphometry, we used American Society of Bone and Mineral Research nomenclature. Mild osteitis fibrosa and osteitis fibrosa, the most frequent forms of renal osteodystrophy, were observed in 13. (22.8%) and 14 patients (24.6%), respectively. Mixed uremic osteodystrophy was found in 7 patients (12.3%), adynamic renal bone disease in 3 patients (5.3%), and osteomalacia in 2 patients (3.5%). In 13 patients (22.8%), reduced bone mass and structural damage without typical signs of renal osteodystrophy, such as endosteal fibrosis or osteoclasia, were detected, and 5 patients (8.7%) showed normal histomorphometric parameters. We concluded that renal osteodystrophy, especially forms with high bone turnover, persisted in many patients after successful renal transplantation. This finding may be due to preexisting conditions, such as duration of dialysis and degree of hyperparathyroidism. Bone disease is increased by corticosteroid and immunosuppressive therapy after renal transplantation and requires close monitoring.