Impaired secretion of parathyroid hormone, but not refractoriness of osteoblast, is a major mechanism of low bone turnover in hemodialyzed patients with diabetes mellitus

Diabetic bone disease is characterized by low bone turnover resulting from either impaired secretion of parathyroid hormone (PTH) or refractoriness of osteoblasts to PTH. The present study was performed to elucidate which factor contributes more to the reduction in bone turnover by comparison between 64 hemodialyzed patients with diabetes mellitus and 106 hemodialyzed patients without diabetes mellitus. Only men were enrolled to avoid the influence of the menstrual cycle on bone metabolism. Serum intact PTH (iPTH) levels were significantly lower in hemodialyzed patients with diabetes than those without diabetes, although no significant difference existed in age, duration of hemodialysis therapy, or serum calcium or phosphate levels. Of the biochemical markers measured, serum intact osteocalcin (iOC) and deoxypyridinoline levels were significantly lower in patients with diabetes, although serum bone-specific alkaline phosphatase (BAP) and pyridinoline levels did not differ significantly between the two groups of patients. When patients were restricted to those with serum iPTH levels greater than 180 pg/mL, this parameter correlated significantly in a positive manner with both serum iOC and BAP levels and negatively with bone mineral density at distal radius 1/3. Regression slopes between iPTH levels and these parameters were not significantly different between the two groups of patients, indicating the absence of refractoriness of bone to PTH in patients with diabetes. In conclusion, our findings suggest that impaired PTH secretion, but not refractoriness of osteoblasts to PTH, may be responsible for the low bone turnover in hemodialyzed patients with diabetes. (C) 2002 by the National Kidney Foundation, Inc.