Pulsatile pattern of thyrotropin-release in normal men.

To evaluate the existence of a pulsatile secretion pattern of thyrotropin (TSH) the 24 h release profile of the hormone was investigated in 7 healthy male subjects by taking blood via an indwelling venous catheter at 10-min intervals. Thyrotropin levels were analysed with high precision by a recently developed immunoradiometric assay (IRMA) able to distinguish euthroid and hyperthyroid TSH-levels. Visual analysis (n = 10.4 peaks/24 h) and the computer assisted evaluation by the Santenprogramme (n = 9.9 peaks/24 h) as well as the Pulsar-programme (n = 7.7 peaks/24 h) revealed an episodic release pattern with a low amplitude of pulses. These preliminary results are highly suggestive of a pulsatile TSH secretion similar to other pituitary hormones.