Bone Turnover Markers Predict Changes in Bone Mineral Density After Parathyroidectomy in Patients With Renal Hyperparathyroidism
Posted: 05/07/2012; Clin Endocrinol. 2012;76(5):634-642. © 2012 Blackwell Publishing
Abstract and Introduction
Objective Patients on long-term dialysis may develop secondary hyperparathyroidism (SHPT), which causes varying degrees of bone mass loss. This condition is treated with parathyroidectomy (PTX). We investigated whether serial serum bone turnover markers could predict changes in bone mineral density (BMD) after PTX.
Design and patients Renal patients on maintenance haemodialysis who received PTX for refractory SHPT (n = 26, male/female: 13/13; mean age: 48·6 ± 10·7 year) and control subjects without SHPT (n = 25) were prospectively followed for 1 year at two tertiary hospitals in Taiwan.
Measurements Serum intact parathyroid hormone (iPTH), bone-specific alkaline phosphatase (BAP) and type 5b tartrate-resistant acid phosphatase (TRAP) were measured serially. Additionally, femoral neck (FN) and lumbar spine (LS) BMD were measured before and 1 year after PTX.
Results After PTX, iPTH levels decreased markedly and persistently. BMDs increased in both the FN and LS, but particularly in the LS. Serum BAP progressively increased to a peak at 2 weeks after PTX. Serum TRAP levels progressively decreased over 6 months after PTX. In univariate correlation analyses, baseline iPTH correlated positively with T-score changes in FN (r = 0·45, P = 0·021) and LS (r = 0·48, P = 0·013). In multivariate regression models, changes in FN T-scores were negatively predicted by baseline BAP levels (r = −0·615, P = 0·005) and baseline FN T-scores (r = −0·563, P = 0·012), and they were positively predicted by baseline TRAP(r = 0·6, P = 0·007). Changes in LS T-scores were positively predicted by baseline TRAP values (r = 0·528, P = 0·01) and negatively predicted by the percentage change in BAP after 2 weeks (r = −0·501, P = 0·015).
Conclusions Parathyroidectomy provided marked, sustained improvements in BMD for up to 1 year. Furthermore, markers of bone turnover predicted 1-year changes in FN and LS BMDs after PTX.