Context: Cortical bone geometry is one of the most important components of bone strength. Excess endogenous PTH or intermittent PTH administration affects cortical bone geometry; however, the changes in cortical bone geometry in patients with primary hyperparathyroidism (pHPT) after parathyroidectomy (PTX) remain unknown.

Objective: The present study was performed to examine the longitudinal effects of treating endogenous PTH excess on cortical bone geometry in postmenopausal patients with pHPT by employing peripheral quantitative computed tomography (pQCT).

Patients: Twenty postmenopausal pHPT patients and thirty postmenopausal control subjects matched for age participated in this study.

Main outcome measures: Volumetric BMD, cortical bone geometric parameters, SSIp (polar strength strain index) and polar cross-sectional moment of inertia (pCSMI) were measured using pQCT at the radius during the year after PTX.

Results: After 1 year, total and cortical BMD significantly increased after PTX in the pHPT group (2.9 and 1.6%, respectively), while they significantly decreased in the control group (-2.1 and -1.3%, respectively). Significant decreases in cortical thickness and area were observed in the control group (-3.0 and -2.5%, respectively). In contrast, the pHPT group showed increases in cortical thickness and area (8.5 and 7.6%, respectively) as well as SSIp 1 year after PTX.

Conclusion: The present longitudinal study showed significant beneficial changes in volumetric BMD, cortical bone geometry and bone strength index after PTX in postmenopausal women with pHPT.