Effect of endogenous subclinical hyperthyroidism on bone metabolism and bone mineral density in premenopausal women

In this cross-sectional study, we evaluated 15 premenopausal women to eluci date whether bone turnover is increased and bone mineral density is reduced due to endogenous subclinical hyperthyroidism. Each patient had normal fre e thyroxine (FT4) and free triiodothyronine (FT3) levels associated with a stable suppression (<0.1 mU/L) of serum thyrotropin (TSH) levels during a p eriod ranging between 6 and 11 months. Metabolic parameters of bone turnove r (serum osteocalcin, bone specific alkaline phosphatase, procollagen I C-t erminal peptide reflecting bone formation; urinary deoxypyridinoline and ca lcium excretion reflecting bone resorption) were assessed, Bone mineral den sity was measured at lumbar 1-4 vertebrae, femoral neck, and the forearm (m idshaft radius and distal radius) by dual energy x-ray absorptiometry. All measurements were compared with 15 healthy age-, height-, and weight-matche d premenopausal women who served as control group. Our findings suggest tha t endogenous subclinical hyperthyroidism is not associated with increased b one turnover, and bone mineral density is not reduced in premenopausal wome n, at least in the short term.