[Lugol's solution and thyroid gland activity in cattle. Determination of the total thyroxine in blood plasma as a method for evaluating thyroid gland activity].

The aim of the present investigations was to examine if an intrauterine treatment with Lugol's solution in cows influences the activity of the thyroid gland. The thyrotropin-stimulation test was used to evaluate the function of the thyroid gland. An injection of 10 I. U. thyreotropin induced within 3 hours an increase of the T4 blood concentrations which reached maximal values 9 hours after the treatment and thereafter decreased again. Thyreotropin concentrations increasing from 5 to 30 I. U. led to a dose-dependent increase of the T4 blood concentrations. The T4 values obtained by 40 i. U. thyreotropin were lower than that induced with 30 I. U. of the hormone. The T4 concentrations increased stronger and remained elevated longer in cows pretreated intrauterine with Lugol's solution than in untreated control cows. The experiments demonstrated that an intrauterine infusion of Lugol's solution may result in an increased activity of the thyroid gland.