Changes in bone turnover markers in primary hyperparathyroidism and response to surgery

INTRODUCTION Involvement of the bone is common in primary hyperparathyroidism. The aim of the study was to assess bone turnover markers in response to surgery for primary hyperparathyroidism. METHODS This was a retrospective study of patients diagnosed and treated for parathyroid disease between 2005 and 2012. Interventions studied were surgery and medical treatment. The main outcome measures studied were serum levels of calcium, intact parathyroid hormone (iPTH), bone-specific alkaline phosphatase, N-terminal cross-linking propeptide of type 1 procollagen (P1NP) and C-terminal cross-linking telopeptides of type I collagen (CTX), both pre- and postoperatively at 6 months and 1 year; bone mineral density (at the spine and hip assessed by dual-energy x-ray absorptiometry after 1 year of treatment. RESULTS A total of 122 (110 female, 12 male) patients (age range 25-91 years) underwent treatment for parathyroid disease during the study period; 30 patients were treated conservatively and 92 proceeded to surgery following localisation studies. Following surgical intervention, P1NP dropped significantly from a mean of 64.68 ng/ml (standard deviation, SD +/- 68.07 ng/ml) preoperatively to 26.37 ng/ml (SD +/- 20.94 ng/ml) and CTX from 0.69 pg/ml (SD +/- 0.44 pg/ml) to 0.15 pg/ml (SD +/- 0.16 pg/ ml) at 6-12 months (P < 0.0001). This change was reflected in improvement in bone mineral density (T scores) of the hip and spine by 43% (P < 0.03) and 38% (P < 0.01), respectively, following surgery. In patients treated conservatively (n = 30), there was no improvement either in the bone turnover markers or bone densitometry scans. CONCLUSIONS Surgery improves bone density in patients with parathyroid disease. Improvement in serum bone turnover markers is seen following parathyroidectomy. The association with bone density needs further evaluation in larger studies.