Monday, July 18, 2011

What are the Main Female Sex Hormones?


Introduction

Female needs not just her own female hormones, but also male hormones in adequate amounts for proper functioning and well-being. The ovaries produce both female and male hormones. The main female hormones are estrogen and progesterone and the main male hormones are testosterone and androstenedione. Let’s review these hormones and their functions for female body functioning in more details.

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Estrogen

Estrogen refers to a group of female "sex" hormones, produced primarily in the ovaries, and to a lesser extent in the body's fat cells. It is important for adolescent sexual development and for regulating the menstrual cycle. Estrogen prepares the uterus for receiving the fertilized egg by stimulating the uterine lining to grow. During days 10 - 14 in a woman's cycle, the uterus is mainly under the influence of estrogen, which begins to climb right before ovulation, which is usually between days seven to fourteen, peaking at ovulation in preparation for a fertilized egg. Estrogen also improves skin tone and reduces vaginal dryness. There are three main types of estrogen that a woman makes: Estradiol (E2), which accounts for 80% of her estrogen, Estriol (E1), and Estrone (E3), each accounting for 10% of the remaining estrogen.

Estradiol is the main source of estrogen for women up until the time of the menopause, and is produced by the ovaries.  From puberty to around the age of 30, the levels of estradiol reach their highest (average blood levels of 450 to 550 pmol/l). After around the age of 30 years the production of estradiol gradually lessens. A few years before the menopause, estradiol blood levels are around 200–300 pmol/l. After the menopause, however, levels of estradiol fall to around 80 pmol/l.

The other source of estrogen (estrone) comes from the adrenal glands, which sit on the top of each kidney. These glands produce a male hormone called androstenedione, which is converted in the fatty tissue to an estrogen  called estrone. The average level of estrone after the menopause is around 100 pmol/l. Since the conversion of androstenedione takes place in the fatty tissue, women with greater amounts of fatty tissue produce higher levels of estrone.

Each individual hormone follows its own pattern, rising and falling at different points in the cycle, but together they produce a predictable chain of events. One egg (out of several hundred thousand in each ovary) becomes 'ripe' (mature) and is released from the ovary to begin its journey down the Fallopian tube and into the womb. If that egg isn't fertilized, the levels of estrogen and progesterone produced by the ovary begin to fall. Without the supporting action of these hormones, the lining of the womb, which is full of blood, is shed, resulting in a period.

The main functions of estrogen are to:
  • Help regulate menstruation.
  • Help in growth and development of female organs.
  • Help prepare the body for fertilization.
  • Stimulate the lining of the womb so that it thickens.
  • Maintain lubrication of the vagina.
  • Help maintain the acid level in the vagina, thereby protecting against infections.
  • Work in conjunction with progesterone to help with the breakdown of the endometrium (lining of the womb) in the second stage of the menstrual cycle.
  • Maintain a supply of calcium to the bones.
  • Help maintain the health of blood vessel walls.
  • Reduce the blood cholesterol level.
  • Bring about the development of secondary sex characteristics, i.e. the breasts and nipples.
  • Influence body shape at puberty, resulting in women having broader hips and narrower shoulders than men, and a tendency to deposit fat on the hips and thighs.
  • Increase elasticity of the skin, promoting performance of hormone collagen.
  • Influence the growth of body hair, so that women have less body hair and more scalp hair than men.
  • Stop the growth of the arm and leg bones, resulting in women being generally shorter than men.

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Progesterone

Progesterone is another female "sex" hormone, produced in the ovaries, that prepares the uterus for a fertilized. Its sudden withdrawal causes the uterus to shed its lining if pregnancy does not occur. While estrogen is high (during days 1-10 of the menstrual cycle), progesterone is at its lowest level. Its levels climb to a peak between days 14 - 24, and then dramatically drop off again just before the start of menstruation. Ideally, women should have five to ten times more progesterone than estrogen in the blood and 40 to 150 times in the saliva. The lower the ratio of progesterone to estrogen, the higher the risk of health problems. Progesterone has the unique ability to change its structural form to become other hormones, allowing it to be converted and utilized by the body to the point of depletion.

The main functions of progesterone are to:
  • Help prepare the body for fertilization and maintain pregnancy. Progesterone during pregnancy and prolactin during lactation promote nest building.
  • Work in conjunction with estrogen, to help with the breakdown of the endometrium (lining of the womb) in the second stage of the menstrual cycle.
  • Help regulate menstruation.
  • Change the mucus produced by the glands in the cervix so that it becomes thick and acidic, thus protecting a potential pregnancy from infection.
  • Aid development of the glands in the breast.
  • Increase water and salt retention, which may lead to painful breasts and weight gain.
  • Improve the immune system.
  • Have a relaxant effect on some of the muscles in the body (i.e. stomach, uterus, and fallopian tubes).
  • Increase production of sebum, leading to more oily skin and spots.
  • Increase the body temperature.

In addition, progesterone may have an impact on mood, leading to an increased irritability. Hence, women often report experiencing changes in mood prior to having a period when the levels of progesterone are at their highest.

Testosterone and androstenedione

Both female and male sex hormones are produced by men and women, but at different levels. Up until the menopause, women have about one-tenth of the amount of male sex hormones that are found in men.

Both testosterone and androstenedione are produced in the ovary, and after the menopause, these hormones go on being produced for a few years. In addition, androstenedione is produced by the adrenal glands (on top of each kidney). The amount of androstenedione produced by the adrenal glands is unchanged after the menopause, although after the menopause it is converted to a form of estrogen (estrone) in the fatty tissue.

The role of male hormones in women is not fully understood, although they have been shown to:
  • Increase libido.
  • Stimulate the growth of pubic, facial and underarm hair.
  • Possibly enhance mood.
  • Increase the density of specific bones (for example, the hip bone).

As can be seen from the above lists, both male and female hormones have a number of functions within the body. Although levels of these hormones change around the time of the menopause, this does not happen suddenly. Ovarian changes occur from around the age of 35 until around the age of 55 to 60 years.

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