SERUM INTERLEUKIN-6 AND BONE METABOLISM IN PATIENTS WITH THYROID-FUNCTION DISORDERS

To determine the possible involvement of interleukin-6 (IL-6) in the b one loss of hyperthyroidism, relationships between thyroid status, bio chemical and densitometric parameters of bone metabolism, and IL-6 wer e studied in female subjects. Patients with hyperthyroidism caused by either toxic nodular goiter or Graves' disease has significantly highe r serum IL-6 concentrations than normal controls. Within the control g roup, serum IL-6 was higher in postmenopausal than in premenopausal wo men, but this influence of menopausal status was not seen in the hyper thyroid patients. The production of IL-6 by blood mononuclear cells wa s higher in cells from the hyperthyroid women. Bone turnover was incre ased in the hyperthyroid patients based on serum osteocalcin and urina ry deoxypyridinoline excretion, and the hyperthyroid group also had re duced radius bone mineral content (BMC). A subgroup of hyperthyroid pa tients who had the lowest BMC (values more than 1 SD below normal age- matched controls) also had serum IL-6 concentrations significantly gre ater than those of hyperthyroid patients showing less reduction of BMC . The correlations observed in this study support the possibility that IL-6 plays a role in mediating the bone loss that results from excess thyroid hormone.