Dose related effects of betamethasone on iodothyronines and thyroid hormone-binding proteins in serum

Earlier studies of the effect of glucocorticoids on thyroid function tests have given different results. This may be due to the fact that varying corticosteroid doses have been used. The present study examined four groups of healthy volunteers, who were given betamethasone in increasing doses (1.5, 3.0, 4.5 and 6.0 mg daily) for 5 days. Definite dose-response relations were found for rT3. The results obtained explain previous variable results. Oral corticosteroids also affected the concentrations of the thyroid hormone-binding proteins but no clear-cut dose-response relation were observed.