Lumbar spine bone mineral density changes in patients with primary hyperparathyroidism according to age and gender

Primary hyperparathyroidism (PHPT) results from excessive secretion of parathyroid hormone (PTH), and catabolic and anabolic effects of PTH on bone may lead to overall deleterious effects on skeleton. The aim of this study was to analyze the changes in lumbar spine bone mineral density (BMD) in patients with PHPT who underwent parathyroidectomy (PTx), and to correlate the main demographics and biochemical parameters with pre- and postoperative BMD values. Two groups of age-matched patients (group A = 14 postmenopausal women; group B = 13 men, overall median age 53 years, range 26-56 years) with confirmed PHPT were enrolled in the study. All patients underwent lumbar (L2-L4 region) spine osteodensitometry using a dual-energy X-ray absorptiometry (DXA) prior to surgery. A significant correlation between alkaline phosphatase (ALP) and PTH (R = 0.73, P = 0.003) was found in group A patients. In group B correlations were found between calcemia and ALP (R = 0.71, P = 0.007), and between osteocalcin and both PTH (R = 0.65, P = 0.01) and ALP (R = 0.59, P = 0.03). No correlation (P = NS) was found between BMD, both basal and postoperative, and age or biochemical parameters. The 1-year BMD were 0.937 +/- 0.115 and 0.940 +/- 0.201 g/cm(2) (P = NS) in group A and B, respectively. A significant (P = 0.03) difference between basal and 1-year BMD was found only in group A, while in group B the difference was not significant. In conclusion, in patients with PHPT bone turnover is increased and consequently the BMD is reduced, but unfortunately PTx does not allow for complete bone restoring. However, in premenopausal women the BMD values of the lumbar spine significantly improve after PTx, suggesting a higher bone sensitivity to serum PTH normalization due to a synergic action with estrogens.