Effects of mild asymptomatic primary hyperparathyroidism on bone mass in women with and without estrogen replacement therapy.

Primary hyperparathyroidism (HPT) presents most commonly as a mild elevation of the serum calcium concentration in an asymptomatic individual. There are conflicting data regarding the effects of mild primary HPT on bone mass. This cross-sectional study was conducted to examine this question further and to determine whether estrogen replacement therapy (ERT) in postmenopausal women with primary HPT might be beneficial. We measured bone mass in 59 women with mild asymptomatic primary HPT, of whom 43 (HPT) had never taken and 16 (estrogen-replaced HPT) were currently taking ERT. We also studied 84 healthy normocalcemic women who were not on ERT (controls) and 45 who were on ERT (estrogen-replaced controls). After adjustment for age, height, and weight, mean bone mass values in the HPT group were significantly reduced in the midradius (20%), distal radius (20%), lumbar spine (17%), and femoral neck (11%) compared with the controls. The estrogen-replaced HPT group had mean bone mass values greater than those in the HPT group, similar to those in the controls, and lower than those in the estrogen-replaced controls. Mild asymptomatic primary HPT results in bone loss from both the appendicular and axial skeleton, and ERT in postmenopausal women with primary HPT may ameliorate this loss.