Sex hormones are produced by the ovaries in the woman and the testes in the man, to give each sex its characteristic appearance. In men, they are responsible for the enlargement of the penis and scrotum at puberty, the development of facial hair and the ability to produce sperm and ejaculate. In women, the sex hormones that are produced for the first time at puberty cause breast enlargement, hair growth in the armpit and groin, ovulation, the start of menstrual periods, and later act to maintain a pregnancy.
If the sex hormones are reduced or lacking, these characteristics disappear. This happens naturally during the female menopause and the male andropause. During the transition from normal sex hormone production to no production in the menopause, there may be some irregular or inappropriate release of these hormones, causing the symptoms commonly associated with menopause such as irregular periods, irritability and hot flushes. After the menopause, the breasts sag, pubic and armpit hair becomes scanty, and the periods cease due to the lack of sex hormones. Men also go through a form of menopause, the andropause, but more gradually and at a later age, so the effects are far less obvious than in the female.
Sex hormones, and many synthesised drugs that act artificially as sex hormones, are used in medicine in two main areas – to correct natural deficiencies in sex hormone production; and to alter the balance between the two female hormones (oestrogen and progestogen) that cause ovulation, to prevent ovulation, and therefore act as a contraceptive.
It is now well recognised that hormone replacement therapy (HRT) in middle-aged women who have entered the menopause significantly improves their quality of life by not only controlling the symptoms of the menopause itself, but by preventing osteoporosis (bone weakening), reducing the apparent rate of ageing, reducing the risk of dementia, and possibly reducing the risk of cardiovascular disease (ie. heart attacks and strokes) after the menopause. Women who have both their ovaries removed surgically at a time before their natural menopause, will also require sex hormones to be given regularly by mouth, patch or implant.
Female sex hormones can also be used to control some forms of recurrent miscarriage and prolong a pregnancy until a baby is mature enough to deliver, to control a disease called endometriosis, and to treat certain types of cancer.
The female sex hormone oestrogen can be given as a tablet, patch, vaginal or skin cream, implantable capsule that is placed under the skin or as an injection.
If the woman has not had a hysterectomy, she will need to take progestogen as a pill or patch in a cyclical manner every month or two. This may result in a bleed similar to that of a natural menstrual period (but usually much lighter), but gives the added benefit of protecting the woman against uterine cancer.
The common sex hormones fall into the categories of oestrogens, progestogens and androgens (male sex hormones).
Oestrogens include dienoestrol, ethinyloestradiol (Estigyn), oestradiol, oestriol (Ovestin), etonogestrel (active ingredient in the implantable contraceptive Implanon), conjugated oestrogen (Premarin), stilboestrol and piperazine oestrone (Ogen). They are used in contraceptive pills, for hormone replacement therapy during and after the menopause, and are usually combined with a progestogen unless the woman has had a hysterectomy. Side effects may include abnormal menstrual bleeding, vaginal thrush, nausea, fluid retention, breast tenderness, bloating and skin pigmentation. These side effects can usually be overcome by adjusting the dosage. They should not be used in pregnancy, breastfeeding, children, and patients with liver diseases or a bad history of blood clots. Care must be used in patients with breast cancer, epilepsy and hypertension.
Progestogens include dydrogesterone (Duphaston), medroxyprogesterone (Provera), progesterone, gestrinone, norelgestren and norethisterone (Primolut-N, Micronor, Noriday). They are used to control abnormal menstrual bleeds, endometriosis, for preventive contraception, “morning-after” contraception, hormone replacement therapy and premenstrual tension. Medroxyprogesterone is an injectable progesterone that may be used for contraception, to treat certain types of cancer and endometriosis. As a contraceptive it is given every three months. Side effects include the cessation of menstrual periods, breakthrough vaginal bleeding, headaches, and possibly a prolonged contraceptive action (up to 15 months). The other progestogens usually have minimal side effects, but they may include headache, abnormal vaginal bleeding, insomnia, breast tenderness, nausea and sweats. They should not be used in pregnancy, liver disease, and patients with blood clots or breast lumps. Care must be used in patients with hypertension and diabetes.
Danazol (Danocrine) is a special type of sex hormone that acts against oestrogen and is used to treat endometriosis, severe menstrual period pain and severe breast pain. Side effects are common and may include acne, weight gain, excess body hair, retained fluid, dry vagina, sweats and the development of a deep voice. It must never be used in pregnancy, or in patients with pelvic infection, liver disease, blood clots or heart failure.
The androgen (male sex hormone), testosterone, is available in synthetic form as a tablets, as an injection (Sustanon), and as implants. They are used to treat conditions such as failure of puberty to occur, pituitary gland dysfunction, impotence, decreased libido (in both sexes), and male osteoporosis. Side effects are unusual, but the prostate gland must be checked regularly for enlargement. They are used in women to treat breast cancer and in both sexes for severe anaemia. Natural lack of the male sex hormone testosterone will cause the man to be impotent and sterile. Synthetic testosterones include fluoxymestrone (Halotestin), mesterolone (Proviron), and oxandrolone (Lonavar). Fluoxymestrone is used to treat breast cancer, osteoporosis and aplastic anaemia. Mesterolone and testosterone are used for male infertility and impotence. Oxandrolone aids short stature, male puberty failure and aplastic anaemia. Side effects may include penis enlargement, infertility, fluid retention, increased body hair and nausea in men, and if used in women irregular periods, deep voice and an enlarged clitoris may develop. They must not be used in pregnancy, heart, liver or prostate disease.
Antiandrogens counteract the action of testosterone. The only common hormone in this group is androcur. It is used to treat excess body hair, severe acne and loss of scalp hair in women, and prostate cancer in men. Side effects may include reduced libido, tiredness, nausea, weight increase and irregular menstrual periods. They must not be used in pregnancy, and patients with blood clots or liver disease.