Spontaneous release of interleukin 1β from human blood monocytes in thyrotoxic osteodystrophy

Hyperthyroidism is a well documented cause of impaired bone turnover characterized by increased osteoblastic and osteoclastic activity, resulting in predominance of bone resorption and in decreased bone mass. Thyroid hormones can carry out a direct effect on osteoblasts which express specific receptors on their surface membrane; differently effect on osteoclast seems to be mediated by local factors, cytokynes released by activated osteoblasts or by bone monocytes cells. Interleukin 1 beta is the first purified cytokyne shown to have bone resorbing activity. In ten thyrotoxic female patients IL 1 beta in the cellular medium of the monocytes blood cells culture has been measured, compared to PYD/cr urinary excretion, and FT3, BGP serum levels, before and after thyrostatic treatment. Ten normal females were studied as control group. The results before treatment showed osteopenia in 20% (DEXA densitometry), increased values of FT3, BGP, IL 1 beta and PYD/cr in patients versus controls (p < 0.001). The thyrostatic therapy obtained normalization of IL 1 beta, PYD/cr, BGP, and FT3 levels. Our data demonstrate that increased thyroid hormone levels in vivo are associated to increased secretion of monocytes cytokynes in vitro and suggest that alterations in local production of bone acting cytokyne may underlie to thyrotoxic osteodistrophy.