Pulsatile secretion of ACTH, GH, LH and TSH in man.

Blood samples were taken every 4 min for 80 min from 5 healthy subjects. Plasma ACTH, GH, LH and TSH were estimated by radioimmunoassays. The mean peak intervals were 11, 12, 13 and 14 minutes respectively and mean peak amplitudes were 25 pg, 1.1 ng, 11 ng and 5.3 muU. Mean durations of ascending and descending limbs of the plasma patterns of these hormones were also measured. The timing of the different hormone peaks appeared to be independent.