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Definition
Hormones are chemical messengers that are essential for normal,
healthy living. They are secreted by endocrine glands, that is organs
containing groups of cells that produce and secrete these hormones
into the bloodstream. Hormones transfer information and instructions as
chemical messages from one part of the body to another.
Sex Hormones in the female
The ovaries are the female reproductive organs (gonads) that release eggs
and female sex hormones. They are in fact the main source of the female
sex hormones production during the reproductive years. The main female
sex hormones are estrogen and progesterone. These hormones are responsible
for the normal sexual development of the female body.
The amount of sex hormones in the blood in childhood is very low but this
starts to increase at puberty because of an increase in Luetinizing
hormone which stimulates the production of ovarian steroids. The breasts,
uterus and vagina start to develop under the effect of these sex hormones.
Sex hormones also work together in an intricate pattern to make the
reproductive cycle function properly. The hormones build up the
lining of the uterus at the beginning of the menstrual cycle, preparing
it for a possible pregnancy. If there is no pregnancy, hormone production
declines. When progesterone drops to a certain level, the lining of the
uterus is shed, resulting in menstruation and the uterus is then ready to
undergo another cycle.
HRT
Author:
M. P. Brincat
Gynaecologist
Last Review: 21/02/2003
Women who still have a uterus must also replace the progesterone
that used to be produced by the ovaries. This progesterone helps to
avoid the risk of developing cancer of the womb that has been associated
with estrogen replacement therapy.
(Estrogen replacement therapy
should only be given to women who have had their uterus/womb removed
since these do not have any risk of uterine cancer.)
When a progestogen is added to the estrogen replacement therapy, the
resulting therapy is known as Hormone Replacement Therapy (HRT).
Women on HRT note that in most cases there is regular uterine bleeding
similar to
a menstrual period.
This bleeding may diminish or stop altogether over time,
however
it is also one of the main differnces from women on estrogen replacement
therapy and it is one of the reasons why compliance is low, women stop the
treatment.
Various HRT regimens are available but the two most commonly used are the:
Sequential (or Continuous-cyclic) HRT
Estrogens are given daily and progestagen is added for 10 to
14 days each month. 80% of women on this therapy will have a
monthly uterine bleeding similar to a menstrual period.
Continuous combined HRT Estrogens and
progestagen are given daily throughout the whole month. The
chance of a menstrual-like bleed is decreased when compared to
women on Sequential (or Continuous-cyclic) HRT
(Cyclic HRT is another option that is rarely used nowadays. It consists of
therapy similar to the Sequential (or Continuous-cyclic) HRT but the
treatment is only given for 25 days each month.)
Weighing the risks and benefits associated with ERT'/HRT should be
individualised for each woman. The decision should be based on the actual
health status of the woman, on her risk/s of developing some serious disease
associated with the menopause. If the potential benefits derived from
replacement therapy outweigh the risks than hormones are indicated.
Estrogen
Author:
M. P. Brincat
Gynaecologist
Last Review: 21/02/2003
Estrogen is the main female sex hormone produced primarily by the
ovaries in women. Estrogen is in fact a group of three hormones, these
being estrone, estradiol and estriol, also known as E1, E2 and E3
respectively.
The main estrogen produced in the ovary is estradiol and it is the
predominant estrogen
premenopausally.
Estrone which is formed from estradiol, is a weaker
estrogen than estradiol. It becomes the main type of estrogen after
the menopause since its levels do not decrease as much as those of
estradiol during this period.
During pregnancy the main form of estrogens is estriol, which is a weak
estrogen as well.
All these naturally occurring estrogens (estrone,
estradiol, and estriol) are C18 steroids secreted by cells in the ovary. These cells are the theca interna and granulosa cells. These cells can originate from the developing ovarian follicle, the corpus luteum or in case of a pregnancy from the placenta. Another pathway whereby estrogens are also produced is by a process known as aromatization of male hormones called androgens (such as androstenedione). This usually occurs in the fat tissue, in the liver and in skin. Ninety-eight percent of the estradiol present in the bloodstream is bound to specific proteins the sex hormone binding globulin and albumin leaving less than 2% free in the circulation. Excretion from the body occurs via the kidneys. The estrogens are first metabolised in the liver (conjugation takes place), thus becoming water soluble. They are then excreted in the bile, reabsorbed in the intestines and finally excreted from the body via the kidneys.
Estrogen stimulates breast development, menstruation and other female
secondary sexual changes.
Estrogens have an effect on the skeleton, they are responsible for the
rapid growth spurt of the teenage years and at the same time they stop
excessive growth by closing the epiphyseal plates of the long bones.
Breast development (both the glandular and the stromal elements) is also
under the influence of estrogens.
This hormone is also responsible
for the brown colouring (pigmentation) of the nipples and areolas
Estrogen is essential for the reproductive life of all women and is
necessary for the cyclical endometrial changes.
It is essential for
ovulation, conception and eventual pregnancy.
It also maintains bone
strength, a healthy skin and helps regulate cholesterol.
Plasma cholesterol is lowered by estrogens which are hence protective
against the hardening up of arterial blood vessel walls, a condition
known as athersclerotic disease which is the cause of more than half
of all mortality in developed countries.
Estrogen replacement therapy
In the menopause estrogen levels decrease. Replacement of estrogens is
termed Estrogen Replacement Therapy (ERT). Estrogens may be taken on
their own (called unopposed estrogens) or in combination with a
progestogen. This latter therapy is called Hormone Replacement Therapy
(HRT).
Estrogen replacement therapy is usually given to women who have had a
hysterectomy (surgical removal of the womb, the uterus) while hormone
replacement therapy is given to those women who have an intact uterus.
Some women may have certain conditions that are contraindications to ERT/HRT use.
These conditions or risk factors include the following:
Known or suspected pregnancy
History of breast cancer
History of hormone sensitive
cancer
Unexplained uterine bleeding
History of blood clotting
disorders
There are other conditions that should also be considered when prescribing ERT/HRT.
These include such conditions as uncontrolled hypertension, fibroids and a family history
of breast cancer.
Side Effects
Some side effects like, breast tenderness, abnormal uterine bleeding, nausea,
fluid retention, headaches (sometimes migraine), dizziness, abdominal bloating,
skin pigmentation, gallbladder problems and mood swings have been associated with
ERT/HRT.
All these side effects can be dealt with using different methods and
in fact most of the side-effects are usually self-limiting, they last only until
the body adjusts to the new hormonal status.
Some women complain of an increase in weight however this is not caused by estrogens.
The increase in weight can be due to fluid retention especially in the hands and
feet, resulting in a temporary weight gain.
Some recent studies show that there may be some increased risk of breast cancer in
patients at risk of this condition. However this risk is still relatively small.
Recent studies have raised questions about the long-term effects of some hormone
replacement therapies and further research is awaited.
Estrogen replacement therapy is available in various forms. It is available as:
Tablets
Patches (deliver the drug via the
skin)
Gel (applied on the skin)
Vaginal cream
Implant (placed in the fat tissue)
The ideal form of replacement depends on the individual woman and should be
discussed with the doctor.
Progesteron
Author:
M. P. Brincat
Gynaecologist
Last Review: 21/02/2003
Progesterone is a female hormone involved in the menstrual cycle.
It works in conjunction with estrogen and is one of the menstrual cycle
regulators.
It prepares the female body for conception and a possible
pregnancy. Progesterone also plays a role in maintaining a pregnancy and
it may aid in preventing miscarriages.
If the amount of progesterone is
not adequate then there are changes that occur in the lining of the uterus,
the endometrium.
Luteal phase defect is the term used when there is
inadequate progesterone production by the ovaries in the second half of
the menstrual cycle.
This condition may either cause a defect in the
implantation of the fertilised egg or else if it implants a miscarriage
could occur.
Once the placenta becomes autonomous it produces sufficient progesterone
in order to
support the pregnancy that is it produces enough progesterone for the
pregnancy to be maintained.
In the perimenopausal years when menstrual cycles start to become irregular
progesterone also plays a role. Progesterone is still produced in the
postmenopausal women albeit in much smaller amounts than in the reproductive
years.
Progesterone is also an important component of hormone replacement therapy
in that it protects the internal lining of the uterus, the endometrium,
from changes that could lead to cancer.
Testosteron
Author:
M. P. Brincat
Gynaecologist
Last Review: 21/02/2003
Testosterone is a hormone, produced primarily in the testes
(by the interstitial cells of Leydig), that stimulates the development
of secondary sexual characteristics and supports the production of
sperm in males.
A smaller amount about 5% is also produced in the
adrenal gland, these are small glands situated on the kidneys.
After menarche (time of first menstrual cycle) women start to produce
testosterone but at a much lower rate then men.
This production
occurs from the ovaries and the adrenals in equal amounts in the form
of testosterone and androstenidione.
Testosterone is important in our
body because it helps to maintain body muscle and also plays an
important part in the sexual drive or libido.
Levels of testosterone
decrease in the menopausal period just like estrogens but not as
sharply as with estrogens. Women may complain of lack of energy and
decreased sexual drive when these levels decrease.
Testosterone helps in osteoporosis, it has the potential of
strengthening bones and it also helps in preserving muscle mass so
decreasing the risk of fractures due to the better muscle tone.
In appropriate doses there do not seem to be any side-effects and
as such monitoring of doses is necessary.
In excessive doses it may
give rise to increases in body hair and loss of scalp hair and an
increase in acne.
High density lipoproteins, the "good cholesterol",
is also decreased and so the risk of heart attacks may increase.
Testosterone may be replaced either via an intramuscular depot
preparation or in the future via a new skin patch which is still being
developed.
SERM
Author:
M. P. Brincat
Gynaecologist
Last Review: 21/02/2003
Selective estrogen receptor modulators (SERMS),
are a relatively new class of synthetic estrogens that act
like estrogen in certain parts of the body (such as the bones) while
having no estrogen-like effect on other parts of the body.
Two different preparations of SERMS are available and they act differently on the various
parts of the body, tamoxifen is used for reduction of breast cancer risk and raloxifene is
used for protection against osteoporosis.
Their use has been highlighted since the recent results of the Women's Health Initiative and
there is an increase in public awareness.
Tamoxifen was originally developed for the treatment of breast cancer patients but it
later emerged that it can also be used as a preventive treatment of breast cancer in women
who are at an increased risk for the condition. This beneficial preventive effect lasts
for 5 years.
Raloxifene helps prevent osteoporosis in women and decreases the risk of fractures in women
with osteoporosis. It helps in the prevention and treatment of osteoporsis.
It has no beneficial effect on other menopausal sysmptoms such as hot flushes or night
sweats.
SERMs should not be used in women who have a history or a tendency to blood clotting
disorders such as deep vein thrombosis.
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