Using a sample of 33 healthy young men, 6 blood samples were obtained in the course of 2 weeks, and testosterone, dihydrotestosterone, and estradiol levels determined. The amount of free testosterone in the saliva was also ascertained for 23 of the subjects. All participants kept a daily record of their sexual activity during the investigational period. An interindividual comparison revealed a significant positive correlation between serum testosterone levels and the frequency of orgasms as well as a significant negative correlation between estradiol concentrations and the frequency of sexual activity without orgasm. The comparison of hormone levels to sexual behavior, prior to and after the individual sampling, reveals significant positive correlations between the serum testosterone and the extent of the free testosterone on the one hand and both the preceding and subsequent frequency of orgasms on the other. The estradiol levels showed a significant negative correlation with both the preceding and the subsequent frequencies of sexual activity without orgasm.

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Six blood samples were taken from each of 33 healthy young men during the course of 2 weeks. From these, the testosterone, dihydrotestosterone, and oestradiol levels were determined. In addition, free testosterone was measured using saliva samples obtained from 23 of the subjects. Both coefficients of variation and variance analyses showed that the inter-individual variability is greater than the intra-individual for all of the hormones. No influence of the day of the week could be ascertained. However, it was discovered that the serum hormone levels dropped with age (weakly significant for oestradiol, insignificant for the androgens) in spite of the subjects being in or near their third decade. The pooled intra-individual correlations between the hormones all fell within the moderate to middle-high positive domain, whereas the inter-individual correlations ranged between highly positive (testosterone to dihydrotestosterone), middle highly positive (free testosterone to total testosterone), and slightly negative (free testosterone to oestradiol).