INCREASED BONE-MINERAL DENSITY AFTER PARATHYROIDECTOMY IN PRIMARY HYPERPARATHYROIDISM

Skeletal involement in primary hyperparathyroidism is characterized by preferential loss of cortical bone, whereas cancellous bone is relatively spared. Little data are available concerning changes in bone density, particularly at sites containing more cancellous bone, after successful parathyroidectomy. Most patients with primary hyperparathyroidism are asymptomatic, but approximately 50% meet one or more criteria for surgery. In a prospective study of 34 patients who met one or more such criteria, bone density rose at all skeletal sites (lumbar spine, femoral neck, and the radius) in the 4 yr after surgery. The lumbar spine, with most cancellous bone, showed a rapid (mean +/- SE, yr 1, 8.2 +/- 2.0%; P < 0.005) and sustained (yr 4, 12.8 +/- 2.8%; P < 0.001) rise. Post menopausal patients were similar (by yr 4, 12.5 +/- 2.7%; P < 0.005). At the femoral neck, with intermediate cancellous and cortical composition, a similar increase was noted (12.7 +/- 3.8% by yr 4; P < 0.01). The distal radius, containing mostly cortical bone, rose modestly (4.0 +/- 1.5% by yr 3; P < 0.05), except in patients with lowest preoperative bone density, where the increase was marked (12.3 +/- 2.6% by yr 3; P < 0.05). In patients meeting surgical guidelines, parathyroidectomy is associated with improved bone mineral density.