RADIOLOGIC AND BIOCHEMICAL CORRELATES OF STEROID-INDUCED BONE CHANGES IN FEMALE RENAL TRANSPLANT RECIPIENTS (RTR)

Abstract

648 A number of biochemical bone markers that have been identified to characterize bone remodeling in normal individuals. However, these markers have not been studied to systematically assess steroid-induced osteoporosis (OS) in RTR. This study evaluated biochemical bone markers in female RTR receiving chronic steroid therapy for at least 6 months and bone mineral density as assessed by DEXA scan. A total of 15 female {10 pre-menopausal (PRE) and 5 post-menopausal (POST)} RTR with stable renal function {PRE: CrCl- 52 ± 21 ml/min and POST: CrCl- 55 ± 21 ml/min} were evaluated during the post-transplant period ranging from 0.5 to 24 years. Patients (age range: 30-68 years) received either chronic methylprednisolone or prednisone therapy. Patients had no active infections, cardiovascular, GI or hepatic disease prior to study inclusion. A first morning urine was collected for determination of pyridinoline (PYR) and deoxypyridinoline (D-PYR). These samples were analyzed by EIA assays and results normalized to urinary creatinine excretion. Serum was collected at 8AM of study day for determination of bone-specific alkaline phosphatase (ALK PHOS) and intact osteocalcin (OSTEO) which were analyzed by EIA assays. In 5/14 RTR (3 PRE; 2 POST), normal DEXA scans were noted with the D-PYR and PYR found to be within normal limits. The ALK PHOS was in the normal limits for 4/5 patients with OSTEO elevated in 2/5 RTR. DEXA scans revealed osteopenia (OP) in 8/15 RTR with OS in 2/15 patients. The PYR were within normal range (13 to 36.2 nM/mM creatinine) for 8/9 patients with abnormal DEXA scans. D-PYR was within normal limits (range:3.0 to 7.0 nM/mM creatinine) in 7/9 patients with either OP or OS. Two RTR had slightly elevated D-PYR concentration (9.94 and 15.7 nM/mM creatinine). The ALK PHOS was within the normal range (13.7 to 27.6 U/L) in 5 patients with abnormal DEXA scans. The OSTEO was elevated in 8/10 patients (15.3-50.0 ng/ml) with OP or OS. This data suggests that the urinary bone markers may not provide accurate information regarding bone resorption in RTR. ALK PHOS fails to provide specific insight regarding bone remodeling. In contrast, OSTEO concentrations appear to correlate with radiologic bone changes. This marker may provide a reliable serial parameter to monitor development of steroid-induced bone OS.