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Monday, 9th January, 2006
New research indicates birth control pill could cause long-term
problems with testosterone hormone levels.
In the January issue of The Journal of Sexual Medicine,
researchers have published a new investigation measuring sex hormone
binding globulin (SHBG) before and after discontinuation of the oral
contraceptive pill. The research concluded that women who used the
oral contraceptive pill may be exposed to long-term problems from
low values of "unbound" testosterone potentially leading to
continuing sexual, metabolic, and mental health consequences.
Sex hormone binding globulin (SHBG) is the protein that binds
testosterone, rendering it unavailable for a woman's physiologic
needs. The study showed that in women with sexual dysfunction,
elevated SHBG in "Oral Contraceptive Discontinued-Users" did not
decrease to values consistent with those of "Never-Users of Oral
Contraceptive". Thus, as a consequence of the chronic elevation in
sex hormone binding globulin levels, pill users may be at risk for
long-standing health problems, including sexual dysfunction.
Oral contraceptives have been the preferred method of birth
control because of their ease of use and high rate of effectiveness.
However, in some women oral contraceptives have ironically been
associated with women's sexual health problems and testosterone
hormonal problems. Now there are data that oral contraceptive pills
may have lasting adverse effects on the hormone testosterone.
The research, in an article entitled: "Impact of Oral
Contraceptives on Sex Hormone Binding Globulin and Androgen Levels:
A Retrospective Study in Women with Sexual Dysfunction" published in
The Journal of Sexual Medicine, involved 124 premenopausal women
with sexual health complaints for more than 6 months. Three groups
of women were defined: i) 62 "Oral Contraceptive Continued-Users"
had been on oral contraceptives for more than 6 months and continued
taking them, ii) 39 "Oral Contraceptive Discontinued-Users" had been
on oral contraceptives for more than 6 months and discontinued them,
and iii) 23 "Never-Users of Oral Contraceptives" had never taken
oral contraceptives. SHBG values were compared at baseline (groups i,
ii and iii), while on the oral contraceptive (groups i and ii), and
well beyond the 7 day half-life of sex hormone binding globulin at
49-120 (mean 80) days and more than 120 (mean 196) days after
discontinuation of oral contraceptives (group ii).
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The researchers concluded that SHBG values in the "Oral
Contraceptive Continued-Users" were 4 times higher than those in the
"Never-Users of Oral Contraceptives". Despite a decrease in SHBG
values after discontinuation of oral contraceptive pill use, SHBG
levels in "Oral Contraceptive Discontinued-Users" remained elevated
when compared to "Never-Users of Oral Contraceptives". This led to
the question of whether prolonged exposure to the synthetic
estrogens of oral contraceptives induces gene imprinting and
increased gene expression of SHBG in the liver in some women who
have used the oral contraceptives.
Dr. Claudia Panzer, an endocrinologist in Denver, CO and lead
author of the study, noted that "it is important for physicians
prescribing oral contraceptives to point out to their patients
potential sexual side effects, such as decreased desire, arousal,
decreased lubrication and increased sexual pain. Also if women
present with these complaints, it is crucial to recognize the link
between sexual dysfunction and the oral contraceptive and not to
attribute these complaints solely to psychological causes."
"An interesting observation was that the use of oral
contraceptives led to changes in the synthesis of SHBG which were
not completely reversible in our time frame of observation. This can
lead to lower levels of 'unbound' testosterone, which is thought to
play a major role in female sexual health. It would be important to
conduct long-term studies to see if these increased SHBG changes are
permanent," added Dr. Panzer.
Dr. Andre Guay, study co-author and Director of the Center for
Sexual Function/Endocrinology in Peabody, MA affirmed that this
study is a revelation and that the results have been remarkable.
"For years we have known that a subset of women using oral
contraceptive agents suffer from decreased sex drive," states Dr.
Guay. "We know that the birth control pill suppresses both ovulation
and also the male hormones that the ovaries make in larger amounts
during the middle third of the menstrual cycle. SHBG binds the
testosterone, therefore, these pills decrease a woman's male hormone
availability by two separate mechanisms. No wonder so many women
have had symptoms."
"This work is the culmination of 7 years of observational
research in which we noted in our practice many women with sexual
dysfunction who had used the oral contraceptive but whose sexual and
hormonal problems persisted despite stopping the birth control
pill," said Dr. Irwin Goldstein, a urologist and senior author of
the research. "There are approximately 100 million women worldwide
who currently use oral contraceptives, so it is obvious that more
extensive research investigations are needed. The oral contraceptive
has been around for over 40 years, but no one had previously looked
at the long-term effects of SHBG in these women. The larger problem
is that there have been limited research efforts in women's sexual
health problems in contrast to investigatory efforts in other areas
of women's health or even in male sexual dysfunction."
To better appreciate the scope of the problem, oral
contraceptives were introduced in the USA in 1960 and are currently
used for reversible pharmacologic birth control by over 10 million
women in the US, including 80% of all American women born since 1945
and, more specifically, 27% of women ages 15-44 and 53% of women age
20-24 years. By providing a potent synthetic estrogen (ethinyl
estradiol) and a potent synthetic progesterone (for example ?
norethindrone), highly effective contraception is achieved by
diminishing the levels of FSH and LH, thereby reducing metabolic
activity of the ovary including the suppression of ovulation.
Several studies over the last 30 years reported negative effects
of oral contraceptives on sexual function, including diminished
sexual interest and arousal, suppression of female initiated sexual
activity, decreased frequency of sexual intercourse and sexual
enjoyment. Androgens such as testosterone are important modulators
of sexual function. Oral contraceptives decrease circulating levels
of androgens by direct inhibition of androgen production in the
ovaries and by a marked increase in the hepatic synthesis of
sex-hormone binding globulin, the major binding protein for gonadal
steroids in the circulation. The combination of these two mechanisms
leads to low circulating levels of "unbound" or "free" testosterone.