Osteoprotegerin and parathyroid hormone as markers of high-turnover osteodystrophy and decreased bone mineralization in hemodialysis patients

Abstract Osteoprotegerin (OPG) has a profound inhibitory effect on osteoclast differentiation and bone resorption. Because high-turnover renal osteodystrophy (ROD) is characterized by increased osteoclast activity, serum OPG concentrations might be used to distinguish between forms of ROD. Twenty-six patients on maintenance hemodialysis therapy underwent a transiliac crest biopsy for evaluation of histopathologic characteristics and histomorphometric studies. ROD was diagnosed as type II (normal or low turnover) or type III (high turnover plus osteoidosis) disease. Bone mineralization density distribution (BMDD) was characterized by measuring the mean trabecular calcium concentration in the biopsy specimen with quantitative backscattered electron imaging. Patients underwent additional dual-energy x-ray absorptiometry (DEXA) of the spine and hip and measurement of such biochemical markers of bone turnover as OPG, intact parathyroid hormone (iPTH), osteocalcin, calcitonin, bone alkaline phosphatase, and cross-laps. OPG levels were significantly reduced in patients with ROD III compared with ROD II (118 ± 38 versus 204 ± 130 pg/mL; P r = 0.43; P P P 2002 by the National Kidney Foundation, Inc.