Infradian variations of salivary estradiol and progesterone in women

Salivary steroids are widely used in endocrine research and clinic. In previous studies we have analyzed the dynamics of salivary estradiol and progesterone in men. There is no published information on infradian cyclic patterns of salivary estradiol and progesterone in women. Saliva samples were collected from 17 young healthy women over 30 consecutive days. Concentrations were measured using radioimmunoassay. The data were statistically analyzed using analysis of rhythmic variance (ANORVA) II method for the presence of cyclic patterns with a potential period length between 3 and 15 days. No significant cyclic patterns were found. The inter-individual variability was higher for progesterone (coefficient of variation, CV 45%) than for estradiol (CV 30%). The intra-individual variability was even higher for both estradiol (CV 67%) and progesterone (CV 87%). These findings show that single time point measurements of these salivary steroids have low informative value and must be taken with caution. Sources of variability beyond the menstrual cycle should be analyzed in further studies.