What are hormones and why is testing required?

Life on earth began as single cell organisms. As life forms evolved, they became multi-cellular. Eventually, life forms had complex organ systems. The problem with multiple organs, is how to coordinate their functioning so that the life form functions normally. For example, when a person walks, how does the left foot know what the right foot is doing? Or if an egg (oocyte) is developing, how does the body know when to release that oocyte so that it can start its journey through the female reproductive track where is can be fertilized?

These are ‘merely’ two examples of the major communication systems that exist within the human body. One system, the musculoskeletal- nervous system is designed for rapid response- don’t let that tiger eat you! The other is the blood and tissue born system of substances called hormones- is it time to have sex yet? A number of hormones have been identified from a number of organs that can affect the chances of a person becoming pregnant or of fathering a pregnancy. The types of hormones can be divided into two groups: those that are involved with the female ovarian reserve and other hormones that can influence achieving a pregnancy.

Ovarian Reserve Testing

There have been a number of hormone tests proposed to measure ovarian reserve testing. There are three tests that are most commonly used: Antral Follicles Count (AFC), Day 3 testing of FSH, LH, estradiol and AMH.

Antral Follicle Count (AFC)

The AFC is done using ultrasound, usually vaginal. The test counts the number of antral follicles in each ovary. The proposed usefulness of the test relies upon the assumption that the number of oocytes in the ovary predicts the quality of the oocytes which really means the number of developing oocytes predicts the number of structurally normal oocytes.

The oocytes are stored, arrested in their development, surrounded by a single layer of cells. When the ovary chooses to use the oocytes, it brings these resting units out of the resting pool and over a five and a half month period of time the oocytes develop the structures they need to create a normal embryo and the layers of supporting cell enlarge, becoming quite complex, and forming a fluid – filled structure called a follicle.

Follicles grow to about an inch at which time the oocyte is fully developed and is ready to be released which is called ovulation. Ultrasounds are excellent at measuring fluid- filled spaces in the body. Any fluid – filled space is called a cyst.

The term cyst is very generic and most of the time, the type of cyst is the information that is needs. For example, fluid filled structures in the ovary which are called a cyst can be an endometrioma (advanced stage of endometriosis), a tumor (benign or malign), or a follicle (normal physiology).

Frequently, ultra sonographers refer to cystic structures in the ovary as cysts but in fact a more accurate term would be a follicle. In the final stages in the development of the oocyte and follicle, the follicle becomes larger enough to accurately visualize by ultrasound. Those follicles measuring 2-9 mm are called antral follicles.

The antral follicle count is simply the number of these follicles seen by ultrasound. This is an indirect way of counting the number of oocytes in the ovary. The assumption is that there is a normal number of oocytes for a normal functioning ovary: too many and there is polycystic ovarian syndrome ( more accurately poly-follicular syndrome); too few and there is a reduced ovarian reserve and perhaps a reduced chance for pregnancy.

The normal AFC varies depending upon the source but 4-8 is a commonly accepted number. The diagnosis of polycystic ovarian syndrome has as one of its diagnostic criteria as an AFC of equal to or greater than 12 antral follicles per ovary.

Day 3 Labs

FSH (follicle stimulating hormone) causes the cells in the follicle that surround the oocyte to multiply and divide. FSH also causes the ovary to convert male hormones in the ovary to the female hormone estrogen. Estrogen has a number of functions during the reproductive cycle. Estrogen circulates in the blood and it is measured by areas in the brain which control the release of FSH. So, if the follicle is not developing normally, there is lower estrogen and the brain increases the release of FSH. In older patients where the follicle is not developing normally due to the oocyte being structurally abnormal, the lower estrogen is seen as increased level of FSH. There are differing levels of FSH that are considered normal but levels between 4 mIU/mL and < 10 mIU/mL. Levels less than 4 suggest that the brain is underperforming whereas levels greater than10 suggest the oocyte is abnormal. FSH has fallen out of favor in determining a reduced ovarian reserve because it fluctuates considerably cycle-to-cycle. So, one high level may not accurately predict ovarian failure, but a normal value may not accurately determine normal oocytes.

LH (luteinizing hormone) causes the outer layer of cells in the follicle (theca cells) to convert cholesterol to male hormones which can then be used by the inner layer of cells (granulosa cells) to produce estrogen. LH also is used to cause the release of the oocyte and to cause the follicle to produce progesterone. Progesterone changes the cells lining the uterus (endometrial cells) so that an embryo can implant. When enough estrogen has been produced for a sufficient period of time, the brain knows the oocyte is ready to be released and it releases a surge of LH which triggers ovulation. The pregnancy hormone, HCG, can do the same thing and therefore is used in infertility treatment to cause ovulation in controlled ovarian stimulation cycles. The surge of LH that is released just prior to ovulation can be measured either through blood testing or, more commonly, by measuring LH in the urine.

Estradiol is produced by the follicle as the oocyte matures. Strangely, estrogen on day three should be low, usually < 30 pg/mL. An elevated day 3 estrogen is indicative of an abnormally developing follicle and thus by implication and abnormal oocyte.

Anti-Müllerian Hormone (AMH) Test

The anti-müllerian hormone (AMH) test has become the hormone of favor for evaluating ovarian reserve. AMH is produced by the cells that develop in the follicle. Thus, the more oocytes, the more follicles, and by corollary, the higher the AMH. If the AMH is low, it implies that there are fewer follicles and common sense would say that the woman had less of a chance for achieving a pregnancy which has been termed a reduced ovarian reserve. AMH has been advertised as a way to decide if oocyte freezing for fertility preservation would help. Nothing is that easy and the AMH story is exemplar of a situation where the theory does not match the reality. AMH was proposed to help decide the chance of having a success if the woman chooses to use IVF. The higher the AMH, the more oocytes, and thus a better chance of having at least one oocyte that can produce a child.  But as has been suggested, the number of oocytes may not correlate with the number of functionally normal oocytes. AMH has been used in IVF and has not been adequately studied to determine if it does identify the group of women who have a reduced functional ovarian reserve. The conclusion from a large number of studies and three meta- analyses suggest the AMH does correlate with fertility potential based upon the concept of reduced ovarian reserve. Unfortunately, the correlation is weak. Contrarily, a high AMH correlates well with the diagnosis of polycystic ovarian syndrome. AMH is useful in determining the dose of FSH to use in IVF and for suggesting an increased risk of ovarian hyperstimulation syndrome for women using FSH in their infertility treatment.

Endocrine Testing Cheat Sheet

Prolactin: Prolactin is a hormone released by the pituitary gland in the brain. Prolactin functions during breast feeding but otherwise is released in very low levels. Normal values for prolactin vary between which lab test is used but commonly accepted levels as being normal are less than 20 ng/mL. Elevated levels can result in breast discharge and irregular cycles.

DHEA-S (dehydroepiandrosterone sulfate): DHEA-S is a male type hormone produced both by the ovary and the adrenal gland. DHEA-S is commonly slightly elevated when women have polycystic ovarian syndrome. However, greater elevations may signal problem in the adrenal glands. Normal values vary widely between 145 to 395 µg/dL.

Testosterone: testosterone is a male hormone that women produce in the ovaries and the adrenal glands. Testosterone is frequently elevated in women who have polycystic ovarian syndrome (PCOS) and is one of the three criteria used to make the diagnosis of PCOS. Testosterone is measured both as the total amount of testosterone in the blood and as the amount of testosterone that circulates freely in the blood. Normal total testosterone for women is 15 to 70 ng/dL and for free is 1- 6 pg/mL.

TSH: TSH (thyroid stimulating hormone) is released by the pituitary gland and controls the functioning of the thyroid gland. Normal vales for TSH are 0.4 to 4.0 mIU/L.

Hormone testing for males: Hormone testing is done less frequently for males because hormone abnormalities are far less common a cause of male factor infertility than for female infertility. The hormones most often tested for males are similar to those measured for females except that testosterone become more important and estrogen not important. FSH and LH are measured and if low suggest an under-functioning brain and if over functioning suggest a testicular failure. Low testosterone suggests under-performing testicles.