CHANGES IN BONE MASS AND METABOLISM AFTER SURGERY FOR PRIMARY HYPERPARATHYROIDISM

BACKGROUND AND OBJECTIVE Bone mass is often reduced in patients with p rimary hyperparathyroidism (pHPT) and is usually partially reversible after parathyroidectomy. However, site specific and overall skeletal b enefits of surgery in mild asymptomatic pHPT remain uncertain. DESIGN Cross-sectional and longitudinal studies. PATIENTS Fourteen patients ( 12 women and 2 men) with pHPT. MEASUREMENTS Baseline bone mass was ass essed al the lumbar spine, left hip and whole body using dual-energy X -ray absorptiometry, and at the left os calcis using broad-band ultras ound attenuation. Changes in bone mass, serum intact PTH and osteocalc in, and urinary pyridinium cross-link excretion were recorded in 10 pa tients followed for 6 months after surgery. RESULTS (1) Cross-sectiona l study: Baseline measurements at the lumbar spine and hip were invers ely related to both the serum PTH concentration and the weight of the parathyroid gland removed at surgery. (2) Longitudinal study: Six mont hs after adenectomy, bone mass had increased significantly at the femo ral neck, greater trochanter, whole body and os calcis, but not at the lumbar spine or Ward's area. Serum PTH, osteocalcin and pyridinium cr oss-link excretion all fell significantly after surgery. The percentag e increment in whole body bone mineral content at 6 months was proport ional to the baseline PTH. CONCLUSION In primary hyperparathyroidism, preoperative reductions and post-operative gains in bone mass are prop ortional to the initial serum PTH concentration. Mild primary hyperpar athyroidism probably does not cause appreciable bone loss at clinicall y relevant fracture sites such as the spine and hip, and in such cases the overall skeletal benefits of surgery are likely to be negligible.