[Circadian and circumannual variations in the level of plasma TSH and prolactin in healthy adult males]

4 healthy young volunteers were submitted to the study of circadian and circannual oscillations of plasma TSH and Prolactin. Our data demonstrated the existence of a circadian rhythm for TSH with acrophase at 04,39 and a circannual rhythm of the same hormone with acrophase in January. While for Prolactin it was possible to detect a circadian rhythm with acrophase at 04,29. We failed to demonstrate any circannual variation of plasma hormonal levels.