CIRCADIAN AND CIRCANNUAL RHYTHMS IN PLASMA HORMONES AND OTHER VARIABLES OF FIVE HEALTHY YOUNG HUMAN MALES

Abstract
Every other month (plasma) and every month (urine) circadian rhythms were documented for 14 mo. Annual changes were validated in the 24 h mean of: plasma FSH [follicle stimulating hormone], annual crest time, Feb.; LH [luteinizing hormone], March; thyroxine, Sept.; cortisol, Feb.; renin activity, April; testosterone, Oct.; urinary 17-hydroxycorticosteroids, March; aldosterone, March; K, May; and sexual activity, Sept. [self-recorded daily]. Plasma prolactin did not show an annual variation. In addition, annual changes in the circadian acrophase (crest time location in the 24-h scale) occurred for some of the documented variables: plasma thyroxine, cortisol, renin activity, testosterone, urinary aldosterone and K.