Adolescent Medicine Update: Oral Contraceptives: Five Vignettes Illustrate Dx and Rx Problems-- and Solutions

Oral contraceptive (OC) pills are frequently prescribed for a variety of clinical purposes. These medications--which contain varying amounts of estrogenand progestin-based compounds--essentially "override" a woman's innate hypothalamic-pituitary-ovarian axis and frequently help ameliorate the effects of a maturing reproductive system while preventing pregnancy. This article reviews the clinical effects of hormonal contraception. Five clinical vignettes are presented that focus on diagnosis and management of problems that may occur when teenagers take OCs.A Quick Review of Oral Contraceptives The typical OC pill contains a combination of an estrogen (usually ethinyl estradiol) and a progestin. To understand how OCs work, remember that ovulation occurs because the hypothalamus secretes gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH). High levels of estrogen and progesterone inhibit secretion of FSH and LH at the level of the hypothalamus (via GnRH) via the pituitary gland. Thus, the body requires sufficiently low levels of estrogen to allow for FSH secretion and follicular maturation, followed by an estradiol surge that prompts secretion of LH to stimulate ovulation (Figure 1). To prevent follicular maturation, a patient requires consistent, high levels of estrogen to provide feedback inhibition on the hypothalamus (which subsequently inhibits FSH secretion). In addition, high levels of estrogen combined with progesterone effectively inhibit the LH surge, which inhibits ovulation. Therefore, the estrogen and progesterone in OCs provide an exogenous level of inhibitory control to the hypothalamus and pituitary gland. The result is decreased FSH and LH secretion and prevention of ovulation. OCs typically come in packages of 21 to 28 pills so that the patient can easily keep track of her menstrual cycle. The 21-day packages require the patient to stop taking pills once all 21 pills have been consumed; after waiting a week (while menses occur), a new package is started. Many adolescents find it less confusing to use a 28-day package (Figure 2). The 7 placebo pills taken at the end of the month allow them to maintain their routine without having to remember to reinstate the regimen the following week. The estrogen component of most OCs is ethinyl estradiol. Over the past 30 years, the concentration of this hormone has dramatically decreased from that used in initial OC studies. After the patient ingests the pill, the liver provides a significant first-pass metabolic effect such that most of the hormone is metabolized before it reaches its target organs. Most commercially available combination hormonal contraceptive pills contain between 20 and 35 μg of ethinyl estradiol. Patients generally do not notice significant differences in clinical efficacy based on a difference of 15 μg of hormone.