Racial differences in parathyroid hormone levels in patients with secondary hyperparathyroidism

Aim: African-Americans (AA) with normal renal function have higher parathyroid hormone (PTH) levels than Caucasians (C). This difference was also noted in cross-sectional studies of patients on dialysis. In this study, we evaluated patients with end-stage renal disease who have just began dialysis and who were not receiving any vitamin D therapy. Methods: A total of 363 patients were recruited (C: 260; AA: 103). All patients had serum calcium, phosphorus, alkaline phosphatase and intact PTH (iPTH) levels measured within 3 months of initiating dialysis. Results: Serum PTH levels were significantly higher in AA vs. C (383 ± 33 vs. 246 ± 19, p < 0.001). This difference was present despite similar calcium, phosphorus and alkaline phosphatase levels between the 2 groups and regardless of gender or diabetes status. However, PTH levels in patients younger than 47 years of age were similar in both groups. Conclusion: PTH levels in ESRD patients over 47 years of age are higher in AA compared to C. The difference is, in part, due to an age-dependent reduction in PTH seen only in C. Further studies are needed to understand the mechanisms of these racial differences and to verify whether they mirror similar alterations at the level of the end-organ tissue.