Hormone Facts

Hormone FactsEstrogens

Human Estrogen

Functions of Estrogen

  • Regrowth of the uterine lining
  • Maintains bladder tissue health
  • Stimulates growth of breast cells
  • Development of female sex organ during puberty
  • Decreases bone breakdown (in association with other hormones)
  • Effects mood, cognition, and concentration
  • Decreases thyroid function
  • Increases fat deposition in tissues
  • Increases blood flow to skin

There are three principal estrogens produced by the human female.

  • Estradiol is the most potent of the estrogens. It is produced in the ovaries before menopause. This estrogen is the one mainly responsible for replacing the lining of the uterus after menses.
  • Estrone is about half as potent as estradiol. It is produced in various places in the body and is the most active estrogen after menopause.
  • Estriol is a very weak estrogen but it is the most abundant in the body. It is produced in the liver from estradiol and estrone. Studies have shown that estriol is effective in estrogen replacement without increasing the risk of breast cancer.

Blood levels of these estrogens vary due to many factors such as time of cycle and age. The ratio of the three estrogens typically is as follows: Estriol 90%, Estradiol 3.4% Estrone 6.6%

Non-Human Estrogens

Animal Sources: Most women who are on hormone replacement therapy receive it in the form of conjugated equine estrogens. These are taken from pregnant mare urine and put into tablet form. Not all of the estrogens contained in these formulations have been identified.

Phytoestrogens: These are natural substances found in plants such as soy. They have a weak effect on the receptors and may actually be beneficial for those women who are experiencing harmful effects of too much estrogen.

Xenoestrogens: These are man-made substances with a very potent estrogenic effect. Examples of these can be found in pesticides, cleaners and pollutants. Unfortunately, these substances are not quickly eliminated and may remain in the body for some time.

Progesterone and Progestins

Functions of Progesterone

  • Development of uterine lining
  • Allows for full development of fetus during pregnancy
  • Activates osteoblasts to increase bone formation
  • Increases libido
  • Protects against breast fibrocysts
  • Protects against breast and ovarian cancer
  • Normalizes blood clotting
  • Acts as a natural diuretic
  • Acts as a natural antidepressant and relieves anxiety
  • Helps thyroid hormone function
  • Is a precursor to other sex hormones and adrenal hormones
  • Helps use fat for energy
  • Raises body temperature

The ovaries produce the majority of progesterone after ovulation. Progesterone prepares the uterine lining for the fetus. If pregnancy does occur, the ovary produces progesterone until delivery, otherwise progesterone production decreases toward the end of the menstrual cycle.


Progestins are synthetic chemical analogs of progesterone. They do not occur in nature and are not produced by the human body. Progestins are most used in oral contraceptives (birth control pills) and have been gaining use for hormone replacement therapy. They made big headlines in July of 2002 when portions of a large study had to be cancelled due to their harmful effects.


Functions of Testosterone

  • Promotes muscle strength and endurance
  • Increases libido
  • Increases energy levels
  • Increases bone density
  • Decreased fat in tissues
  • Promote a general feeling of well being

Testosterone is produced in the ovaries and adrenal gland of the female. It is one of the major hormones responsible for creating sexual desire in both males and females.

Hormone Imbalance

Cause: The vast majority of hormone imbalance in women has a singular cause – Aging. As a woman ages, the ovaries and eggs age as well. After the age of 35, it becomes increasingly difficult for the ovary to develop an egg to maturity and release it. The body responds by making more estrogen to stimulate the ovaries. Whenever the ovaries do not produce an egg, no progesterone is produced. As a result, a woman experiences the effects of too much estrogen and too little progesterone. Also as a result of aging, the ovaries produce less testosterone over time.

Eventually the ovaries stop producing eggs altogether, usually between the ages of 48 and 52. This is called menopause. The ovaries stop producing estrogen but estrogen is still produced in other parts of the body. The need for estrogen to help the reproductive processes is gone and lower levels of estrogen are sufficient to serve the non-reproductive processes.

Other factors: PMS is estimated to affect 50 to 80 percent of women in the United States. The incidence in less developed countries is much lower and is mainly attributable to a different lifestyle. Diet and stress are the two main factors. The US diet is rich in processed foods, hydrogenated oils, and sugars. It is deficient in fiber, fruits and vegetables. Proper diet with nutrient supplementation will have a marked effect on PMS. Stress is known to increase levels of some hormones and decrease levels of others. This by itself can cause many hormone imbalances.


Excess Estrogen (also known as estrogen dominance)

  • Irregular or Heavy bleeding
  • Breast tenderness
  • Depression
  • Fatigue
  • Fibrocystic breast
  • PMS
  • Decreased libido
  • Endometriosis
  • Water retention and bloating
  • Fat gain around hips and thighs
  • Breast and uterine cancer1
  • Accelerated aging
  • Poor concentration
  • Hair loss
  • Headaches
  • Increased blood clotting (increased risk of stroke)
  • Insomnia
  • Thyroid dysfunction

Excess Progesterone

  • Euphoria
  • Drowsiness
  • May lead to progesterone tolerance

Progesterone Deficiency

  • Irregular or Heavy bleeding
  • Breast tenderness
  • Depression
  • Fatigue
  • Fibrocystic breast
  • PMS
  • Decreased libido
  • Endometriosis
  • Water retention and bloating
  • Fat gain around hips and thighs
  • Breast and uterine cancer1

Progestins vs. Progesterone

Since progestins are not identical to human progesterone, the actions and side effects will be different.

Comparison of the Effects of Progesterone and Progestins

Conditions Human Progesterone Progestin

  • Increases sodium and water in body cells
  • Causes loss of mineral electrolytes from cells
  • Causes intracellular edema
  • Causes depression
  • Increases birth defect risks
  • Causes loss of scalp hair
  • Causes thrombophlebitis embolism risk
  • Decreases glucose tolerance
  • Causes allergic reactions
  • Increases risk for cholestatic jaundice
  • Causes acne, skin rashes
  • Protects against endometrial cancer
  • Protects against ovarian cancer
  • Protects against breast cancer
  • Normalizes libido
  • Causes growth of scalp hair
  • Improves lipid profile
  • Facilitates thyroid hormone action
  • Prevents implantation of fertilized ovum
  • Is essential for successful pregnancy
  • Is essential for myelinization of nerves
  • Restores normal sleep patterns
  • Is a precursor of other steroid hormones
  • Usually effective in treating PMS

Hormone Balance

The ultimate biologic response reflects the BALANCE OF ACTIONS of the different hormones with their respective receptors.

Progesterone is the evolutionary safeguard that enables you to enjoy the benefits of estrogen without side effects. It prevents an excess of estrogen buildup in the body. The two really go together.

Estrogen and progesterone work best together in their proper ratio. One cannot optimally function without the effect of the other. The normal ratio of free estrogen to free progesterone is approximately 20 to 1 after ovulation, during which time progesterone is the dominant hormone.1

Hormone Testing

When replacing a substance normally found in the body it is very important to perform tests in order to properly determine dosing. If a physician determines that someone is deficient in potassium, the patient is started on potassium replacement and then tests are done to see if the level has risen into the normal range. The consequences could be disastrous if no follow-up testing is done. That being said, it makes no sense to place someone on hormone replacement therapy without monitoring levels. How much is too much?

Blood vs. Saliva Testing: As stated above, the action of a hormone is dependent on the amount of free hormone in the blood. The obvious answer of taking a blood sample and testing it does not always work. Many labs cannot determine the amount of free hormone in the system and show only the total.

Hormones pass into saliva by passive diffusion. Since the proteins that bind hormones cannot diffuse into saliva, only the free hormones can pass. Numerous studies have shown a good correlation between saliva and free hormone blood levels.

Hormone Replacement Therapy (HRT)

Bio-Identical vs. Natural

Definitions: Bio-Identical hormone means a hormone that is chemically identical to the one produced in the human body.

Natural means present in or produced by nature.

Bio-Identical hormones are by definition natural. They are found in the human body. There are however, no good sources of bio-identical hormones in nature to be used in HRT. Drug makers start with plant material, usually soy or yam. There are hormones in these plants that are similar to human hormones. These are harvested, refined and chemically converted in a laboratory so that the molecule is identical to the one produced in the human .

Commercially Available

These products can be purchased in any pharmacy. They are mass manufactured and heavily promoted to physicians by the drug companies.


Oral: Most women who are on hormone replacement therapy receive it in the form of conjugated equine estrogens. These are taken from pregnant mare urine and put into tablet form. Not all of the estrogens contained in these formulations have been identified but the vast majority are not human bio-identical.

Patches and Creams: These formulations contain a bio-identical estrogen but usually only estradiol. They do not mimic the natural balance in the body.

Progesterone and. Progestins

Oral: The vast majority of prescriptions in the United States are for a progestin called medroxyprogesterone. It is available by itself or in combination with conjugated equine estrogens.

Creams: Progesterone in available in cream form with a concentration of 8% or 80mg/gm. This product can be quite expensive if not covered by insurance.

Compounded Products

These products are compounded by Custom Scripts Pharmacy. Since each prescription is specially made for the patient, the dosage can be tailored to meet individual needs.

Dosage forms: There are four usual routes of administration for HRT. Capsules and transdermal creams are most often used. Sublingual (under the tongue) tablets and vaginal suppositories can also be used. Hormones are well absorbed through the skin. The fat tissue under the skin can act as a reservoir for the hormone, therefore creams usually produce the most stable blood levels.

Estrogens: Bi-est and Tri-est

Bi-est is a combination of Estriol and Estradiol usually in a ratio of 80:20 respectively. Tri-est is a combination of Estriol, Estradiol, and Estrone usually in a ratio of 80:10:10 respectively.

Oral: Estrogens are well absorbed from the GI tract with very little being broken down in the stomach. Both Bi-est and Tri-est are used orally. By convention, physicians usually prescribe these combinations in strengths such as 0.625mg, 1.25mg, and 2.5mg.

Transdermal cream: Tri-est is not recommended for use in transdermal creams. Estrone is absorbed more rapidly then Estradiol or Estriol leading to unbalanced levels. Bi-est is the combination of choice for topical administration. Dosages are similar to those used in oral administration.


Oral: Progesterone is not well absorbed through the GI tract. Much of it is broken down before it reaches the blood stream. Dosages typically used are 50mg, 100mg, or 200mg per capsule.

Transdermal cream: Typical dosages used in creams are 25mg, 50mg and 100mg.


Like progesterone, testosterone is not absorbed well from the GI tract. Dosages for testosterone vary widely.

Where do I start?

If possible, find a doctor that is knowledgeable in the use of bio-identical hormone replacement therapy. You will be in the hands of someone already experienced in treatment with these hormones.

Option two would be to find a doctor that you are comfortable with and would be willing to learn about BHRT. Two very good sources of information are the books by Dr. Taylor and Dr. Lee listed in the references.

Detail Section:

Menstrual Cycle:

When a baby girl is born, she has all the eggs her body will ever use, perhaps as many as 450,000. They are stored in her ovaries, each inside its own sac called a follicle. As she matures into puberty, her body begins producing various hormones that cause the eggs to mature. This is the beginning of her first cycle; it’s a cycle that will repeat throughout her life until the end of menopause.

Let’s start with the hypothalamus. The hypothalamus is a gland in the brain responsible for regulating the body’s thirst, hunger, sleep patterns, libido and endocrine functions. It releases the chemical messenger Follicle Stimulating Hormone Releasing Factor (FSH-RF) to tell the pituitary, another gland in the brain, to do its job. The pituitary then secretes Follicle Stimulating Hormone (FSH) and a little Leutenizing Hormone (LH) into the bloodstream which cause the follicles to begin to mature.

The maturing follicles then release another hormone, estrogen. As the follicles ripen over a period of about seven days, they secrete more and more estrogen into the bloodstream. Estrogen causes the lining of the uterus to thicken. It causes the cervical mucous to change. When the estrogen level reaches a certain point it causes the hypothalamus to release Leutenizing Hormone Releasing Factor (LH-RF) causing the pituitary to release a large amount of Leutenizing Hormone (LH). This surge of LH triggers the one most mature follicle to burst open and release an egg. This is called ovulation. Many birth control pills work by blocking this LH surge, thus inhibiting the release of
an egg.


As ovulation approaches, the blood supply to the ovary increases and the ligaments contract, pulling the ovary closer to the Fallopian tube, allowing the egg, once released, to find its way into the tube. Just before ovulation, a woman’s cervix secretes an abundance of clear “fertile mucous” which is characteristically stretchy. Fertile mucous helps facilitate the sperm’s movement toward the egg.

Inside the Fallopian tube, the egg is carried along by tiny, hairlike projections, called “cilia” toward the uterus. Fertilization occurs if sperm are present as the live egg reaches the uterus.

Uterine Changes

Between midcycle and menstruation, the follicle from which the egg burst becomes the corpus luteum (yellow body). As it heals, it produces the hormones estrogen and, in larger amounts, progesterone which is necessary for the maintenance of a pregnancy. Within a few days, if the uterus is not pregnant, the follicle turns white and is called the corpus albicans.

Progesterone causes the surface of the uterine lining, the endometrium, to become covered with mucous, secreted from glands within the lining itself. If fertilization and implantation do not occur, the spiral arteries of the lining close off, stopping blood flow to the surface of the lining. The blood pools into “venous lakes” which, once full, burst and, with the endometrial lining, form the menstrual flow. Most periods last 4 to 8 days but this length varies over the course of a lifetime.

Endocrinology 102:

Hormone binding:

Hormones traveling in the bloodstream are either bound to proteins or unbound (free). Binding proteins act as a reservoir so that as the free hormone moves into cells, the proteins release some hormone and the amount of free hormone does not appreciably change. Estrogen, progesterone and testosterone are mostly bound by Sex Hormone Binding Globulin (SHBG). Thyroid hormone is bound by Thyroid Binding Globulin (TBG). Albumin, which is a large protein in the blood, also binds to hormones but not nearly as much as the others mentioned.