Bone histomorphometry and indicators of bone and mineral metabolism in wait-listed dialysis patients

Abstract

The aim of this study was to evaluate the associations between bone histomorphometry and bone volume measured by dual-energy X-ray absorptiometry (DXA) in wait-listed dialysis patients. Further, the circulating markers of mineral metabolism and bone turnover were compared. Bone biopsies were performed on 61 wait-listed dialysis patients. Plasma samples were obtained for indicators of mineral metabolism and bone turnover. Bone mineral density (BMD) was determined by DXA and bone histomorphometry was performed. Bone histomorphometry could be determined in 52 patients (72% men, 54% on hemodialysis and median dialysis vintage 18 months). Adynamic bone disease was present in 21% of patients and 4% had osteomalacia. High turnover bone disease (mixed uremic osteodystrophy and osteitis fibrosa) was observed in 48% of patients (17% and 31%, respectively). 10% of patients had normal bone histomorphometry while 17% had mild osteitis fibrosa. Mineralization defect was found in 33% of patients. There was a strong correlation between femoral neck (FN) T-score and histologically measured cancellous bone volume (p = 0.004), FN T-score having a good negative predictive value for low cancellous bone volume. Plasma osteocalcin levels were significantly higher in the high-turnover group and lower in the mineralization defect group (p = 0.014 and p = 0.02, respectively). Our study confirms the high frequency of abnormal bone histology in wait-listed dialysis patients. Low bone turnover was less common than previously reported. Noninvasive markers had a limited value for assessing bone histology, whereas femoral BMD reflected bone volume well.