Androgens in Health and Disease.pdf - E Library

Chapter 14/Androgens and Sexual Function 269
ANDROGENS IN WOMEN
Developmental Aspects
Whereas androgens increase during the course of pubertal maturation in females, in
comparison to males they start at a lower level and show a doubling of T through the stages
of pubertal maturation compared to the 18-fold increase in T for boys (65). There is an
added complexity in the female; T production, which is predominantly from the ovary,
shows a cyclical pattern accompanying ovulatory cycles. In an established and regular
adult ovulatory cycle, T levels rise during the follicular phase and are at a maximum
approximately for the middle third of the cycle, declining during the final third to reach
the nadir during the first few days of the next follicular phase. Within the middle third,
T levels may be relatively sustained or, as reported in some studies, show more discrete
peri-ovulatory peaks. There is presumably some individual variability in this respect.
There is a lack of evidence of what happens to T levels in adolescent postmenarcheal
young women who have not yet established their regular adult pattern of ovarian cyclicity.
Ankaberg and Norjavaara (66) studied T levels in a group of girls ranging from prepuberty
to 2 yr postmenarche. Before puberty, they found T levels correlating with DHEA-S
levels suggestive of the adrenals being the main prepubertal source of T. After the onset
of puberty, T correlated more strongly with estradiol (E 2), suggestive of the ovary as the
main source of T. However, although T levels were higher in mid and late puberty than
in early puberty, the T-to-E 2 ratio was higher in early puberty than later.
When we consider peripubertal and early-adolescent T levels and their relationship
to sexuality in females, we are again largely dependent on the work of Udry and his
colleagues. Once again, their findings are somewhat confusing, comparable to their male
studies. In their first cross-sectional study of white girls in the 8th, 9th, 10th grades, Udry
et al. (67) found a relationship between T levels and measures of sexual interest and
frequency or occurrence of masturbation, but not to whether they had experienced sexual
intercourse. In their more recent longitudinal study of black and white postmenarcheal
adolescent females (68), T levels and increase in T were related to the transition to first
intercourse, but not to measures of sexual interest or masturbation. As is the case for their
male studies, this discrepancy is not easy to explain. However, given the greater complexity
of the female ovarian cyclicity, particularly in early adolescence, there is greater
scope for methodological confusion. In the first cross-sectional study, blood samples
were collected between d 5 and 9 of the menstrual cycle, whereas in the later study,
samples were collected between d 2 and 8. In neither case was the mid-third of the cycle,
when T levels are maximum, sampled, and the 2- to 8-d sampling in the second study may
have resulted in lower levels than would have been obtained using the 5- to 9-d sampling.
The closer sampling is to the midcycle maximum, the more likely one is to find correlations
with T-dependent behavior, as it is the maximum levels that are most likely to
determine the behavior. The association between follicular T levels and transition to
coitus may be reflecting some marker status of T level relevant to the ovarian cycle,
rather than direct effects of the T.
As with males, one might expect T to be more directly related to sexual interest and
self-directed behaviors, such as masturbation, than to sexual interaction with a partner.
Therefore, it is of interest that in the report on age of onset of masturbation, cited earlier
(46), relating onset of masturbation in females to age at menarche, and in males ot age
at spermarche, the picture is very different for females than for males, in whom age of