A Significant Association between Parathyroid Adenoma Volume and Bone Mineral Loss at Distal Forearm.

Introduction: The cortical bone is the most severely affected site in patients with primary hyperparathyroidism (PHPT) and thus, a low bone mineral density (BMD) is predominantly observed in distal forearm. Several studies have investigated potential associations between the weight of the gland and bone mineral loss. In this study, we wanted to investigate the relationship between parathyroid adenoma (PTA) volume and bone mineral loss.

Methods: All patients with a diagnosis of PHPT who were operated at our hospital, and with a histologically proven single PTA were retrospectively analyzed. Z-scores were used as the main variable in our analysis to eliminate the effects of age, sex and gonadal status on BMD.

Results: Total of 153 patients who met the inclusion criteria were eligible for the study. A significant negative correlation between the PTA volume and z-score for distal third of the radius (DR) (p = 0.006, r = -0.297) was shown. The cut-off value of gland volume for predicting cortical bone mineral loss was 9043.2 mm³. There was also a significant negative correlation between the 24-hour urine calcium and z-scores for lumbar vertebrae and total hip. A significant negative correlation was found between preoperative 25-hydroxy vitamin D levels and the PTA weight.

Conclusions: As the first study that evaluated any possible association between the volume of a parathyroid adenoma and bone mineral loss in patients with PHPT, we found a significant negative correlation between DR z-scores and resected gland volume. Since the volume of a PTA can also be determined by a preoperative US, our findings may be helpful during the preoperative evaluation of a patient with a preliminary diagnosis of PHPT.