Circannual oscillations of function compared with morphometric changes in the thyroid gland of the Wistar-rat.

To investigate biological rhythms of the thyroid gland circannual oscillations of thyroxine (T4), triiodothyronine (T3), and thyrotropin (TSH) were compared in serum samples of untreated young male Wistar-rats with the circannual changes of thyroid weights and with the relative proportion of colloid, epithelium, and interstitium of the thyroids. Animals were kept under standard environmental conditions, however, lighting conditions simulated the natural day-night changes. Thyroid weights, T4, T3, and TSH showed a statistically significant circannual rhythm with maxima in winter and spring and minima in summer and autumn.

[Effect of mestranol and chlormadinone acetate on TSH, T4, TBC and FT4 index in Turner syndrome].

In 19 patients with Turner's syndrome aged from 12 to 24 years (average age 17.0 years) the influence of mestranol and chlormadinone acetate on both basal and TRH stimulated TSH secretion, total thyroxine (T4), thyroxine binding capacity (TBC) and free thyroxine index (FT4-I) by means of sequential stimulation test (0.5 g arginine hydrochloride/kg body weight, 25 micrograms GnRH and 200 micrograms TRH) was investigated.