Female hormones and menopause

The menopause occurs due to a fall in oestrogen levels which affect the menstrual cycle and causes a range of physical and emotional changes.

But what is oestrogen and what role does it play in the menopause?

To learn more about oestrogen we need to understand about the female hormones and their role in the endocrine system.

Endocrine system

This is the name given to an information system, similar to the nervous system, which controls every function in the body.

It consists of a series of glands which secrete hormones that help to regulate the body. These glands include the pituitary gland, thyroid gland and the adrenal glands.

Each of these glands produces a type of hormone which attaches to a specific type of tissue and enables communication between cells related to that tissue.

They are circulated around the body via the blood and cause a series of changes once they reach their target organ.

Hormones are chemical messengers which control various functions in the body, e.g. metabolism and reproductive functions in both men and women.

These hormones contain instructions which they transfer from cell to another. But each hormone only affects those cells which have been genetically coded to receive these instructions.

Hormones are affected by a variety of factors which include stress, disease, infection and blood sugar levels.

In regard to the menopause: it is changes within the female hormones which cause the characteristic symptoms of the menopause.

These hormones are oestrogen and progesterone.

Female sex hormones

The hormones oestrogen and progesterone play an important role at various times throughout a woman’s life. These include puberty, pregnancy and the menopause.

They along with tiny amounts of the male hormone testosterone are produced by the ovaries which form part of the female reproductive system.

Oestrogen and progesterone are known as the ‘sex hormones’and have an important function in ovulation and menstruation. They are accompanied by two other hormones – Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH).

These hormones individually rise and fall at different times during the menstrual cycle but they combine together to form a logical sequence of events.

This sequence involves the ovaries.

Ovaries

Each baby girl is born with thousands of eggs stored in her ovaries. These remain inactive until the onset of puberty when the pituitary gland secretes the hormones FSH and LH. These hormones act as a trigger for the ovaries to produce oestrogen and progesterone.

Every month until the menopause the ovaries release a single egg (known as an ovum) which travels down the Fallopian tubes and into the uterus.

This process is known as ovulation and is a time when the woman is most likely to conceive. In the days leading up to this the walls of the uterus thicken in preparation for a pregnancy.

If this egg is fertilised then it results in a pregnancy. The egg attaches itself to the walls of the uterus and begins a nine month developmental process into a baby.

If the egg is not fertilised then oestrogen and progesterone levels drop and without these the egg dies. The lining of the uterus is eliminated from the body along with the unfertilised egg as a blood flow or menstrual period.

This function continues until the early stages of the menopause or the perimenopause. It becomes erratic and as a result of this causes lighter, irregular periods.

The drop in oestrogen has a dramatic impact upon a woman’s health.

Oestrogen

This is the main hormone produced by the ovaries which is responsible for a range of functions which includes reproduction and egg production.

Oestrogen is blamed for conditions such as premenstrual tension (PMT) but it plays an important role throughout every woman’s life and is not to be taken lightly.

This includes a range of protective effects against osteoporosis and heart disease as well as maintaining the normal functioning of the breast, bladder, uterus and vagina.

Oestrogen is not one hormone but actually three which includes:

• Estradiol
• Estrone
• Estriol

Estradiol

This is the main component of oestrogen. It acts as a form of growth hormone for tissue of reproductive organs such as the uterus, vagina and the Fallopian tubes.

It plays an important role during puberty in that it facilitates the development of secondary sexual characteristics. These include distribution of body fat, breast development and widening of the hips.

This hormone remains constant in the early stages of the menstrual cycle; but rapidly increases on the day that Luteinising hormone (LH) is released as part of ovulation.

Estradiol is usually present in the body but this hormone decreases during the menopause.

Estrone

This hormone is produced by the ovaries and the adrenal glands and is the only chemical that remains in the body following the menopause.

Estriol

This is produced in large quantities during pregnancy and is considered a good replacement for women who are unable to tolerate estradiol and estrone.

Progesterone

This hormone is produced by the ovaries during ovulation and the placenta during pregnancy. It performs a range of functions which includes foetal support during pregnancy and regulation of the menstrual cycle.

Progesterone levels fall during the menopause which causes various biological symptoms, for example hot flushes.

Follicle stimulating hormone (FSH)

This hormone is secreted by the pituitary gland and travels to the ovaries where it stimulates the follicles into egg production.

FSH rises at various intervals in the menstrual cycle and when it does, it causes eggs within the ovaries to produce small amounts of estradiol.

This stimulation is then sent as a signal to the pituitary gland which causes it to slow down FSH production.

But if there is a low supply of eggs which do not respond to stimulation then the pituitary gland produces ever increasing amounts of FSH in order to trigger a reaction.

High levels of FSH can be an indication that the menopause has started; although if this occurs in a women under 40 then it can be a sign of premature menopause or ‘premature ovarian failure’.

A simple test can be carried out to check FSH levels but it is not conclusive. Other tests are required to determine if the menopause has started or not.

Luteinising hormone (LH)

This hormone is also secreted by the pituitary gland and works in conjunction with follicle stimulating hormone (FSH) to trigger egg production in the ovaries.

It also acts as a form of support during pregnancy in that it regulates oestrogen and progesterone levels during this time.

LH and FSH levels rise during the menopause.

Testosterone

This is the name given to the male hormone which is also present in women albeit in small amounts.

It is produced by the ovaries but levels of this fall after the menopause.