DER TSH-RESERVE-TEST AN DER RATTE

Abstract

A rebound of I131-uptake by the thyroid gland after a thyrostatic treatment may be taken as evidence of an unimpaired pituitary TSH-secretion. The iodide uptake in vivo and the iodide accumulation in vitro were studied in rat thyroids following a short-term treatment of the animals with carbimazole. The experiments served as models for the clinical method of assaying the pituitary TSH-reserve. The total iodide uptake reaches a peak 36 hours after the end of a carbimazole treatment and returns to normal after 96 hours. The rebound of the iodide accumulation has a similar time course. Extending the carbimazole treatment from 6 to 12 days leads to a definite increase in the peak iodide accumulation while the peak of the total iodide uptake was not significantly increased. The duration of the re-bound-phase is not changed by prolonged carbimazole treatment.