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HORMONES! So many Hs… Here is what you need to know.
You are not alone if you left your first reproductive endocrinology consultation with your head swirling with acronyms (FSH, LH, TSH, AMH, IVF, IUI, ICSI, AST, PGS). Yikes! This short guide to reproductive hormones will clear your brainwaves and help increase your understanding of fertility testing and treatment.
The Endocrine System is a series of glands that produce and release hormones into the blood stream that have a target organ. This system controls a wide range of bodily functions including metabolism, growth, development, sexual function, reproduction and lactation. Disturbances in this system may lead to infertility.
When decoding hormones, it is helpful to think about where the hormones come from (where they are produced or “secreted”) and what their target organ is.
The Pituitary Gland
The pituitary gland resides in the brain and is the master controller of the endocrine system. It produces hormones that stimulate various glands or organs in our body. Too much or too little of this stimulation can cause disease.
- FSH (follicle stimulating hormone) is released by the pituitary gland and binds to receptors on the ovary or testicle. It is one of two hormones called gonadotropins – hormones that stimulate the gonads (ovaries or testicles). Both men and women have the same gonadotropins. FSH is responsible for growth and maturation of eggs in the ovary. The growing egg then releases estrogen as it matures, which sends signals back to the pituitary gland to lower FSH production. As the ovary ages and the eggs number declines, less estrogen is produced, which is in turn sensed by the brain and FSH hormones goes up to try and increase the signal to the ovary to make an egg. When women have no eggs remaining (menopause), they do not have eggs to make estrogen, so FSH is very high. Women in menopause therefore will have very high FSH levels (brain trying to get the ovary to work) but low estrogen levels (ovary does not have any eggs left to make estrogen). In the absence of periods, high FSH with low estrogen is diagnostic of menopause. FSH levels vary throughout the cycle in a premenopausal patient, and the FSH level early in a cycle correlates with a woman’s ovarian reserve. If the FSH level is high early in the cycle on day 3 of a period, that is concerning for an aging ovary. It also raises concerns about infertility and how someone might respond to fertility treatments. When trying to get many eggs to grow at the same time for an IVF procedure, the medications used contain FSH to aid in the stimulation.
- LH (luteinizing hormone) is the other gonadotropin. It also binds to receptors on the ovary or testicle to stimulate cells that produce male-type hormones such as testosterone and DHEAS. LH levels vary throughout a women’s menstrual cycle, and a mid-cycle peak of LH causes ovulation. When using a urine ovulation predictor kit, you are detecting that LH peak to estimate ovulation day. Some women have high levels of LH throughout the cycle, whichcan cause irregular ovulation and bothersome symptoms related to high testosterone levels. This is known as polycystic ovarian syndrome (PCOS) and is one of the most common causes of infertility in young women.
- TSH (thyroid stimulating hormone) is produced by the pituitary gland and binds to the thyroid gland in the neck. High TSH levels mean the thyroid gland is not making enough thyroxine, which is important for metabolism. The pituitary senses low thyroxine and increases stimulation to try to compensate. So, high TSH means hypothyroidism (low thyroid function) and low TSH means hyperthyroidism (overactive thyroid). Severe thyroid disorders may cause women to quit ovulating as well as complications during pregnancy. More subtle thyroid issues might slightly increase some pregnancy risks such as miscarriage. Typically, TSH is followed closely in women with infertility.
- Prolactin is another hormone made in the pituitary gland. It should only be high during lactation and pregnancy. If the pituitary gland overproduces prolactin, FSH and LH levels are suppressed, so egg development and ovulation might temporarily cease. This is why most women do not get menstrual cycles during the first few months of breastfeeding. If prolactin is overproduced when not breastfeeding, irregular ovulation and infertility can occur. High prolactin hormone levels can be lowered with medication in order to restore normal ovulation if this occurs.
Gonadal (Ovarian and Testicular) Hormones
- AMH (anti-müllerian hormone) is secreted directly by the ovary. It is also secreted by the testicular cells in a male fetus to suppress formation of female reproductive organs (but that function is not related to its current use in fertility testing). It is a test of ovarian reserve, or remaining egg number. It is a good predictor of the timeline for opportunity for pregnancy and can indicate if women have low or high numbers of eggs remaining. It also correlates well with how someone will respond to mediations used to stimulate egg development in the ovary (for example if few or many eggs can stimulated in IVF). AMH has NOT been associated with the quality of eggs, and AMH declines as women get older. Lower AMH means menopause is closer. High AMH does not always mean normal fertility or good quality eggs. For example, some women with high AMH values have ovulation problems and infertility related to polycystic ovaries, and some women with low AMH values have high quality eggs, just not many of them remaining. AMH can be useful to understand how much time you have to attempt fertility treatment and how you might respond to those treatments. AMH levels should not be used alone to diagnose infertility.
- Estradiol is another hormone secreted by the ovary. It is secreted in the developing egg follicle, and the highest levels are seen right before ovulation. Menopausal women have low estrogen levels because there are no egg follicles growing. In fertility treatments that stimulate the ovary to make many eggs at once, estrogen level can become very high. Generally, higher levels of estrogen in IVF indicate more eggs are retrieved. Estrogen thickens the uterine lining in preparation for the implantation of an embryo.
- Progesterone is a hormone secreted by the ovary after ovulation. It prepares the uterine lining to implant an embryo. If no implantation occurs, the progesterone level falls and the uterine lining sheds, causing menstrual blood flow. Women who do not ovulate do not make progesterone and therefore do not have regular periods. Progesterone levels are high during pregnancy because the placenta also makes this hormone.
- Testosterone is made in the ovary and the testicle. Women have testosterone levels that are significantly lower than males. If women have high testosterone levels, this can indicate an abnormality in the reproductive hormones and may lead to problems with ovulation. High testosterone levels also cause bothersome symptoms in women such as acne or excess hair growth on the body. In men, testosterone production by the testicle is important for normal sperm formation. Low testosterone in men may be caused by a disruption in the endocrine system and may cause difficulties with erections or ejaculation. Men who use testosterone injections might relieve these sexual symptoms, but taking testosterone lowers the sperm count in men and should be avoided while couples are attempting pregnancy.
That is a brief overview of the most important reproductive hormones! You can see that an overproduction or underproduction of hormones can have consequences for fertility. This complex system is interrelated and is investigated as part of any couple experiencing infertility.
Dr. Sara Barton, Best Shot's Medical Advisor, is a doubly board certified reproductive endocrinologist and obstetrician gynecologist at the Colorado Center for Reproductive Medicine in Denver, CO.