Comparison of adenoma and gland hyperplasia on bone mineral density in primary hyperparathyroidism

Abstract

Background: Parathyroid gland adenomas or hyperplasia can cause primary hyperparathyroidism where increased levels of parathyroid hormone (PTH) lead to increased bone resorption. Parathyroidectomy can attenuate or reverse this bone loss. This study compares the difference in gland histology on Bone Mineral Density (BMD) following parathyroidectomy.

Methods: A retrospective cohort study of patients with primary hyperparathyroidism comparing BMD before and after parathyroidectomy between patients with single-gland adenomas and hyperplasia on histological examination. BMD was measured using Dual-Energy X-Ray Absorptiometry (DXA) at the lumbar spine, total hip, femoral neck, total forearm, distal one-third radius and ultra-distal radius. T-Scores and Z-Scores were calculated and compared.

Results: A total of 118 patients were included (Adenoma Group n = 82; Hyperplasia Group n = 36). On presentation, a lower proportion of patients with adenomas were symptomatic with renal calculi (14.5% versus 35.3%, p = 0.013). The Hyperplasia Group had lower pre-operative BMD in their lumbar spine (p = 0.031), femoral neck (p = 0.002), total forearm (p = 0.022), and distal one-third radius (p = 0.009) and higher rates of osteoporosis (p = 0.023). The Adenoma Group had higher post-operative BMD gains in the femoral neck (3.3% versus 0.4%, p = 0.029).

Conclusion: Primary hyperparathyroidism caused by hyperplasia presents with worse BMD loss than that of adenoma. Following parathyroidectomy, adenoma demonstrates greater BMD recovery compared to hyperplasia. BMD gain is primarily within mixed cortical/trabecular bone of the hip whilst no relative gain was observed in the spine or forearm, reflecting different manifestations of bone resorption between these histological variants.