INCREASED BIOCHEMICAL MARKERS OF BONE-FORMATION AND RESORPTION IN PRIMARY HYPERPARATHYROIDISM WITH SPECIAL REFERENCE TO PATIENTS WITH MILD DISEASE

Objectives. To evaluate the impact on bone turnover of primary hyperpa rathyroidism (pHPT) with special reference to patients with mild pHPT, using biochemical markers of bone formation and resorption. Design. A longitudinal study of patients with pHPT before and one year after su rgical treatment. Setting. The Departments of Internal Medicine and Su rgery, Lund University Hospital. Subjects. Forty consecutive patients with pHPT. Thirty of these patients had mild pHPT and are reported sep arately. Data on bone mineral was also compared to a reference populat ion, Intervention. All patients were operated upon and restudied one y ear later. Main outcome measures. Bone resorption and formation was st udied by means of the serum concentrations of the telopeptide of the c arboxyterminal region of type 1 collagen (ICTP) and of alkaline phosph atase (ALP), osteocalcin and the carboxyterminal propeptide of type 1 procollagen (PICP), respectively. Bone density was measured at the dis tal radius by single photon absorptiometry (SPA). Results. Bone format ion markers consistently decreased after parathyroid surgery: ALP from 3.51 +/- 0.23 to 2.94 +/- 0.21 mu kat L-1 (P < 0.05), osteocalcin fro m 6.15 +/- 0.53 to 2.89 +/- 0.23 mu g L-1 (P < 0.001) and PICP from 12 6.4 +/- 10.9 to 96.0 +/- 6.5 mu g L-1 (P < 0.001). In parallel, the IC TP concentration, reflecting bone resorption, decreased from 5.10 +/- 0.54 to 3.94 +/- 0.34 mu g L-1 (P < 0.001). There was not any signific ant change in distal radius bone mineral 1 one year after surgery. In the subgroup of patients classified as mild pHPT, a significant decrea se was noted for osteocalcin, PICP and for ICTP but not for ALP, witho ut significant changes in variables reflecting distal radius bone mine ral content. Glomerular filtration rate was inversely correlated to se rum levels of intact PTH, ionized calcium, alkaline phosphatase, osteo calcin and ICTP and directly correlated to the 1.25-dihydroxy-vitamin D concentrations. Conclusions. pHPT is associated with substantial cha nges in circulating levels of biochemical markers of bone formation an d resorption. These findings are also present in patients with mild pH PT. Renal function should be considered in the evaluation of the impac t of pHPT on bone turnover.