EFFECT OF HORMONE REPLACEMENT THERAPY ON BONE-MINERAL DENSITY IN POSTMENOPAUSAL WOMEN WITH MILD PRIMARY HYPERPARATHYROIDISM - A RANDOMIZED,CONTROLLED TRIAL

Background: Most patients with primary hyperparathyroidism are postmen opausal women. The presence of osteopenia in persons with mild primary hyperparathyroidism is considered an indication for parathyroidectomy . No prospective, controlled trials have assessed medical therapies fo r osteopenia in primary hyperparathyroidism. Objective: To examine the effects of estrogen-progestin therapy (hormone replacement therapy) o n bone mineral density and biochemical indices in postmenopausal women with mild primary hyperparathyroidism. Design: Double-blind, randomiz ed, placebo-controlled trial. Setting: University teaching hospital. P atients: 42 postmenopausal women with mild primary hyperparathyroidism . Intervention: Patients were randomly assigned to receive either conj ugated estrogens, 0.625 mg/d, and medroxyprogesterone, 5 mg/d, or plac ebo. Measurements: Bone mineral densities of the total body, lumbar sp ine, proximal femur (femoral neck, Ward triangle, trochanter), and pro ximal forearm were measured every 6 months using dual-energy x-ray abs orptiometry. Biochemical indices of bone turnover and calcium metaboli sm were measured at baseline, 6 months, and 2 years. Results: In the p lacebo group, bone mineral densities of the total body and the proxima l forearm decreased significantly from baseline (mean +/- SE, -2.3% +/ - 0.7% [P = 0.005] and -3.5% +/- 1.2% [P = 0.01], respectively). At th e other sites, bone mineral density also tended to decline. In the hor mone replacement therapy group, bone mineral density increased from ba seline in the total body (1.3% +/- 0.4%; P = 0.004), lumbar spine (5.2 % +/- 1.4%; P = 0.002), and femoral neck (3.4% +/- 1.5%; P = 0.05). Th e between-group differences in bone mineral density at the end of the study ranged from 3.6% to 6.6% and were significant at all sites (P > 0.001 and P < 0.05) except for the Ward triangle (P = 0.06). In the ho rmone replacement therapy group, serum alkaline phosphatase levels dec reased by 22% (P = 0.0004 compared with baseline), urinary hydroxyprol ine excretion decreased by 42% (P = 0.0004), urinary N-telopeptide exc retion decreased by 54% (P = 0.001), and urinary calcium excretion dec reased by 45% (P = 0.007). Hormone replacement therapy did not change levels of serum ionized calcium or intact parathyroid hormone. Conclus ions: Although hormone replacement therapy has little effect on serum calcium levels, it suppresses bone turnover, reduces urinary calcium e xcretion, and increases bone mineral density throughout the skeleton i n postmenopausal women with mild primary hyperparathyroidism. This the rapy is thus an important management option for these patients.