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Glossary of Terms

Arteriosclerosis — This is the thickening and stiffening of arteries, the blood vessels that carry nutrients and oxygen to the body from the heart. This can restrict blood flow to the brain, the heart, and other organs. Another term for arteriosclerosis is “hardening of the arteries.” Usually, healthy arteries are elastic and flexible. However, with aging, the walls of the arteries can stiffen and harden.  

Atherosclerosis — A specific form of hardening of the arteries, whereas fats, cholesterol, and other substances invade and accumulate on and in the walls of arteries. The term for this accumulation is “plaque.” Plaque narrows arteries and reduces blood flow. Sometimes the plague can burst and form a clot. Atherosclerosis can affect the heart vessels and blood vessels anywhere in the body, although there are effective treatments. Living a healthy lifestyle is essential to help prevent atherosclerosis.

Early perimenopause A condition in which the ovaries begin to function irregularly after the age of 40 and before the age of 45 years.

Perimenopause A medical term that means “around menopause.” Perimenopause is the time a woman’s body is transitioning to menopause. The time of onset of perimenopause varies from woman to woman. Signs of progression toward menopause are the onset of menstrual irregularity and hot flashes. During perimenopause, the level of the hormone estradiol rises and falls unevenly and unpredictably. Women do not ovulate regularly during perimenopause, thus menstrual cycle intervals may shorten or lengthen. Women may also experience disordered sleep and vaginal dryness. Treatments are available to manage these symptoms. Once a woman has experienced 12 consecutive months with no menstrual period, the perimenopausal period has concluded, and the condition is now officially considered menopause. (The medical condition known as “early perimenopause” is the onset of perimenopause before age 40.)

Estradiol — A hormone produced by the ovaries that supports fertility and is important for maintaining healthy bones, heart, skin, and hair. Often abbreviated “E2,” estradiol is the most necessary form of human estrogen, made primarily by the ovaries. E2 is essential to the development of a woman’s reproductive system, which includes the breasts, uterus, fallopian tubes, and vagina. The level of E2 in the blood is higher in younger women during their reproductive years; the level of the blood is very low after menopause. 

Follicle stimulating hormone (FSH) — A hormone produced in the pituitary gland, located beneath the brain, that stimulates the ovaries to function normally. Hormones are chemical messengers that travel through your blood.

In women, FSH stimulates the ovaries to grow follicles. Follicles are fluid-filled sacs that contain the egg. In addition, FSH stimulation causes ovarian follicles to produce the hormone estradiol. If the FSH level in the blood is high in a woman, it most likely means the ovaries are not functioning normally. Likewise, if the FSH is very low, it most likely means the pituitary is not functioning normally. Therefore, clinicians order this test in conditions such as :

  • Missing menstrual periods
  • Ovarian insufficiency
  • Early or late puberty

FSH is a specialized test to be interpreted by trained clinicians. The clinician interprets the results in the context of the specific health situation. Laboratories report FSH results in milli-international units per milliliter (mIU/mL).  

FSH levels in the blood change with the phase of the menstrual cycle. Normal levels are:

  • 1.4 to 9.9 mIU/mL (follicular phase)
  • 6.2 to 17.2 mIU/mL (ovulatory peak)
  • 1.1 to 9.2 mIU/mL (luteal phase)
  • 19.3 to 100.6 mIU/mL in ovarian insufficiency or after menopause

Hormones — Chemical messengers in the blood that have important actions in the body to maintain health.

Luteinizing hormone (LH) — A hormone produced in the pituitary gland that stimulates the ovaries to function normally and induces ovulation. LH is determined through a specialized test and should be interpreted by trained clinicians in the context of the specific health situation. Laboratories report LH results in milli-international units per milliliter (mIU/mL).  

LH levels in the blood change with the phase of the menstrual cycle. Normal levels are:

  • Follicular phase: 1.68 to 15 IU/mL
  • Midcycle peak: 21.9 to 56.6 IU/mL
  • Luteal phase: 0.61 to 16.3 IU/mL
  • Primary Ovarian Insufficiency or postmenopausal: 14.2 to 52.3 IU/mL

Menstrual cycle — The menstrual cycle is the monthly hormonal cycle a female’s body goes through to prepare for pregnancy. The menstrual cycle is counted from the first day of one period up to the first day of the next period. The four phases of the menstrual cycle include menstruation, the follicular phase, ovulation, and the luteal phase. Knowing when in the menstrual cycle a woman is most likely to conceive can increase the chance of pregnancy. Although the number of days between the start of one period and the start of the next normally varies between 21 and 35 days, a “typical” cycle is 28 days. Menstrual cycle intervals shorter or longer than this range are not normal and deserve evaluation by a clinician.

Osteoporosis — A medical condition in which the bones become brittle, weak, and fragile from loss of tissue, typically as a result of hormonal changes, or deficiency of calcium or vitamin D. In fact, bones may get so brittle that a mild fall, coughing, or bending over may lead to broken bones, with fractures most often occurring in the spine, wrist, or hip. Bones are an active living and changing tissue constantly building up and tearing down cells to remodel bone. In osteoporosis, the building up of bone falls behind the tearing down — hence, weaker bones. Importantly, osteoporosis is silent until the later stages of the disorder when fractures start happening much more easily than expected. Estradiol deficiency is a major contributor to osteoporosis in women.

Ovaries — The ovaries are small, oval-shaped glands located in a woman’s pelvis that produce eggs and store them for future use. The ovaries also make hormones that control the menstrual cycle and are important in keeping bone, heart, brain, skin, and hair healthy.  

Ovarian antral follicle —  A follicle is a fluid-filled sac in the ovary that contains an egg. When a follicle is ready to release an egg, it is about 25 mm in diameter. Antral follicles are immature follicles that are still growing. Although antral follicles are small — about two to nine millimeters in diameter — they can be seen and measured by fertility specialists. 

Ovarian antral follicle count (AFC) — A measure of the number of antral follicles in the ovaries. Ultrasound scans can determine the number of eggs a woman has at the start of a menstrual cycle. The number of antral follicles is a parameter of ovarian response and predicts the response to drugs given to stimulate the growth of ovarian follicles. High-quality ultrasound equipment is required to perform this test accurately. An antral follicle count results predict a woman’s chance of successful IVF treatment.

Primary ovarian insufficiency (POI) — A rare condition in which the ovaries begin to function irregularly before the age of 40 years.

Progesterone — A naturally occurring hormone produced by the ovary after ovulation.

Progestogen A hormone that is meant to mimic progesterone and act as it does in the body.

Testosterone — A steroid sex hormone that stimulates development of male secondary sexual characteristics, produced mainly in the testes, but also in the ovaries and adrenal cortex.

In men, it’s thought to regulate sex drive (libido), bone mass, fat distribution, muscle mass, and strength, and the production of red blood cells and sperm.

Menstrual and Ovarian Health

Follow the Evidence

POI Fast Facts

POI is a hormonal deficiency. It is not menopause.

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Understanding estradiol deficiency begins with understanding ovarian hormones.

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The Evidence

Research can help you make evidence-based decisions.

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Think Again

Educate and advocate. Your doctor may not be an expert.

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