The reproductive processes in the male and female are under the complex control of numerous hormones. In the female, follicle stimulating hormone (FSH), luteinizing hormone (LH), progesterone, prolactin, estrogen, progesterone, bhCG, and others control the menstrual cycle and support the developing embryo. Several of these hormones are discussed here.
Follicle Stimulation Hormone (FSH)
FSH is the hormone responsible for "recruiting" ovarian follicles and stimulating/supporting their growth. It is also the chemical component of the injectable medications used to stimulate the ovaries in in vitro fertilization cycles.
Gonadotropin releasing hormone is released by a gland in the brain known as the hypothalamus, which stimulates the pituitary gland to produce FSH and luteinizing hormone (LH). Levels of these hormones decrease as estrogen and inhibin increase during follicular development (feedback). In other words, as the follicles reach maturity less FSH is needed and the rise in estrogen signals the pituitary to reduce production.
FSH is measured on day three of the cycle and a normal value is less than 10 IU/L. Levels over 12 are associated with lower pregnancy rates and usually indicate reduced ovarian reserve and impending menopause.
Luteinizing Hormone (LH)
The LH level is normally measured on day three of the menstrual cycle. LH levels rise abruptly immediately before ovulation and stimulate the release of the egg. LH is produced by the pituitary gland, which is controlled by the hypothalamus. Medications such as Ovidrel and Pregnyl (hCG) mimic the action of LH and are administered to stimulate ovulation.
Estrogen levels are measured using a blood test. As follicles develop, estrogen levels rise to stimulate the endometrium (lining of the uterus) to grow in preparation for the fertilized egg. Estrogen levels are used in conjunction with ultrasound measurements to insure that women receiving ovulation-inducing medications are responding properly. Very high estrogen levels in a woman receiving fertility medications may indicate a potentially serious complication known as ovarian hyperstimulation syndrome. As follicles develop, they produce increasing amounts of estrogen roughly in proportion to the number of healthy follicles.
Estrogen has numerous other effects on female metabolism including stimulation of endometrial development.
Human Chorionic Gonadotropin (bhCG)
b-HCG is a hormone produced by the placenta as the embryo develops. Elevated levels indicate the presence of an ongoing pregnancy. A precipitous rise or fall of this hormone can indicate pregnancy loss.
Progesterone in Oil and/or Prometrium
Progesterone is a hormone produced by the ovaries during the menstrual cycle to help prepare the uterus to accept and support an embryo. The corpus luteum, a gland composed of tissue from the follicle after ovulation, synthesizes estrogen and begins to produce progesterone.
Progesterone causes the lining of the endometrium to thicken and increases its blood supply. Progesterone is administered to women undergoing assisted reproductive procedures (IVF). After a pregnancy has been established, the placenta produces progesterone. Side effects of progesterone can include moodiness, and fluid retention, depression, irritability, and hypoglycemia.
Elevated levels of prolactin, in the absence of pregnancy, may indicate hypothyroidism or a tumor on the pituitary gland and cause irregular or absent ovulation. Prolactin is a hormone that stimulates milk production in the female and its level rises during pregnancy.
The tumor is usually benign and can sometimes be removed via surgery or prolactin levels are lowered using medication (bromocriptine). Once the elevated levels are normalized, the chances of pregnancy are usually excellent.
Thyroid hormones are produced by the thyroid gland and levels are measured with blood tests. Hypothyroidism (low levels) can cause an increase in prolactin and negatively impact fertility. Hyperthyroidism can negatively affect the male's sperm.
Women with polycystic ovarian syndrome (PCOS) typically have elevated androgen levels (testosterone, DHEAS sulfate, cortisol, 17-hydroxyprogesterone). Increased levels of these male hormones causes increased hair growth on the body and irregular or absent ovulation. Ovaries of PCOS patients have a "bumpy" or cystic appearance. PCOS can cause lack of ovulation.
One goal in the treatment of the PCOS patient is to lower androgen levels. The insulin sensitizing drug metformin has been successful in lowering insulin levels and normalizing androgen production by the ovaries.
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