Infradian dynamics and variability of salivary testosterone in men and women

Abstract

Background. The dynamics of testosterone levels exhibits several cyclic patterns with various period lengths. Circadian and circannual rhythms of testosterone are known in both genders. Among infradian rhythms only the circalunar cycle in women is widely accepted. In our previous studies we have found a circatrigintan (30 days) and a circavigintan (20 days) cycle in men. Whether cyclic patterns with higher frequencies are present in the dynamics of testosterone levels in men or in women is unknown. Aim. To analyze the infradian dynamics of salivary testosterone in both genders for the presence of cyclic patterns. Subjects and methods. Seventeen young and healthy women and 15 men were asked to collect saliva samples during 30 consecutive days. Testosterone levels were determined using radioimmunoassay, Analysis of Rhythmic Variance II (ANORVA II) was used for statistical analysis. Potential period lengths of 3 – 15 days were evaluated. Results. The dynamics of salivary testosterone showed high intra-individual variability in both genders (coefficient of variation – 28% in women and 26% in men). ANORVA II analysis showed no significant rhythms, although a weak circaseptan cyclic pattern has been found in women. Discussion. Our results showed no significant infradian cyclic variation with a period between 3 and 15 days. Further studies should concentrate on potential longer periods. Described intra-individual variability of testosterone levels in both genders should be considered in endocrine research.