Terms Description
AMS Questionnaire A questionnaire about symptoms of low testosterone that is useful for diagnosis and for monitoring the effects of treatment. AMS stands for Aging Males' Symptoms.
Androgen A hormone that controls the development and maintenance of male sexual characteristics. Testosterone is an androgen.
Atherosclerosis The buildup of cholesterol and plaque, on the inner walls of arteries. This can lead to the arteries (e.g. coronary arteries supplying blood to heart muscle) becoming hardened and narrowed.
Benign prostatic hypertrophy A non-cancerous enlargement of the prostate gland that can occur in older men.
Cardiovascular disease A group of diseases that involve the heart or blood vessels (veins and arteries). Cardiovascular diseases include high blood pressure, atherosclerosis (hardening of the arteries), stroke and heart attack.
Central obesity Excessive abdominal fat around the waist.
Diabetes A group of metabolic disorders in which the body no longer produces insulin or uses insulin ineffectively. Diabetes is characterised by abnormally high blood sugar levels.
Dyslipidaemia Unbalanced blood lipid levels (abnormal amounts of cholesterol and/or fat in the blood).
Erectile dysfunction (impotence) Inability to achieve or sustain an erection long enough to engage in sexual intercourse.
Erythrocytosis An abnormal increase in the number of red blood cells circulating in the body. Erythrocytosis may be a side effect of testosterone therapy.
Follicle-stimulating hormone (FSH) One of two hormones produced by the pituitary gland that act on the testes (the other is luteinising hormone). FSH stimulates the testes to produce sperm.
Gonadotrophin-releasing hormone (GnRH) A hormone produced by the hypothalamus that stimulates the release of luteinising hormone and follicle-stimulating hormone from the pituitary gland.
Gynaecomastia Abnormal enlargement of the breasts in men.
Hormone A chemical messenger produced by one tissue that has a specific effect on a second tissue, for example to control growth or function. An androgen is a hormone that controls the development and maintenance of masculine characteristics.
Hypertension High blood pressure.
Hypogonadism (low testosterone) A clinical syndrome that results from the failure of the testes to produce sufficient testosterone and the normal number of sperm. Primary hypogonadism can be due to a genetic cause (e.g. Klinefelter syndrome) or to damage to the testes (such as from injury or infection). Secondary hypogonadism involves an imbalance in the hormonal system responsible for producing testosterone and may result from Kallmann syndrome or other conditions which affect the regions of the brain that are involved in this system (the hypothalamus and the pituitary gland).
Hypothalamus A complex region of the brain with many essential functions. One of these is to produce gonadotrophin-releasing hormone which stimulates the pituitary gland to produce luteinising hormone and follicle-stimulating hormone, which act on the testes.
Insulin resistance A condition where the body is less able to respond to insulin.
Kallmann syndrome A genetic disorder that affects 1 in 10,000 men (it can also affect women, though more rarely). Kallmann syndrome causes a form of secondary hypogonadism where the hypothalamus does not produce sufficient gonadotrophin-releasing hormone. In turn this means the pituitary does not make sufficient luteinising hormone and follicle-stimulating hormone resulting in low testosterone and sperm production by the testes.
Klinefelter syndrome In Klinefelter syndrome the testes develop poorly and during puberty the testosterone level does not rise as it usually would in other teenage boys. The symptoms vary from person to person but muscle growth and body/facial hair may not develop normally. Additionally, the voice may not break and some teenagers with Klinefelter syndrome may develop breast tissue (gynaecomastia). Klinefelter syndrome is one of the most common genetic conditions known, affecting 1 in 500 to 1 in 1000 men.
Libido The experience of sexual desire.
Lower urinary tract symptoms (LUTS) Symptoms in the male that comprise storage, voiding and post-urination affecting the lower urinary tract. There may also be the need to pass urine frequently at night.
Luteinising hormone (LH) One of two hormones produced by the pituitary gland that act on the testes (the other is follicle-stimulating hormone). LH stimulates the testes to produce testosterone.
Metabolic syndrome A combination of medical disorders such as high blood pressure, high blood sugar levels, unbalanced blood lipid levels and central obesity (fat around the waist). Metabolic syndrome increases your risk of cardiovascular disease and diabetes.
Osteoporosis A disease in which the bones become brittle and prone to fracture. Although it is most common in post-menopausal women, osteoporosis is a long-term consequence of low testosterone in men.
Pituitary gland A small gland at the base of the brain. The pituitary gland releases numerous essential hormones including luteinising hormone and follicle-stimulating hormone which stimulate the testes to produce testosterone and sperm.
PubMed One of the main on-line biomedical reference databases containing over 22 million citations.
SHBG Sex hormone-binding globulin is a protein in the blood that binds tightly to testosterone. Testosterone that is bound to SHBG is not free to do its job. SHBG levels increase with aging and this contributes to the condition of low testosterone.
Side effect An unintended effect of a drug treatment.
Sleep apnoea A sleeping disorder characterised by repeated pauses in breathing during sleep.
Testes or testicles The male reproductive glands that produce testosterone and sperm.
Testosterone An essential male hormone (androgen) produced in the testes that plays a crucial role in the health and well being of our bodies. Testosterone is responsible for typical male sexual characteristics and is required by all men for a healthy life physically and psychologically.