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What is testosterone?
What controls the production of testosterone from the testis ?
What is a normal testosterone concentration ?
What symptoms may I have of hypogonadism ?
What causes hypogonadism ?
What treatment is available for hypogonadism ?
Are there side effects ?
Where can I learn more?

What is testosterone?

Testosterone is the male hormone which is mainly produced by the testis. Small quantities are made in other organs (eg adrenal gland), but in a man this contributes only a small amount of the total. Testosterone is a hormone which is released into the blood which will have effects on other parts of the body. Testosterone is important for:

  1. Controls development of male genitals before birth
  2. When levels increase at puberty, secondary sexual characteristics develop  eg deepening voice, muscular development, facial hair etc
  3. In adulthood it determines sexual drive, sperm production and fertility. It is also5 important in maintaining facial and pubic hair, and keeping muscles and bones healthy. It may also be important in protecting the heart.
  4. In old age testosterone concentrations fall. Although this is common, it is unclear whether it is inevitable and what part it plays in ageing

When men have a lack of testosterone the condition is termed hypogonadism

What controls the production of testosterone from the testis ?


A part of the brain called the pituitary release a hormone called lutenising hormone (LH) which controls testosterone production. Another hormone from the pituitary called follicle stimulating hormone (FSH), along with testosterone stimulates sperm production. Slightly higher in the brain the hypothalamus releases a hormone called gonadotrophin releasing hormone (GnRH) which controls production of LH and FSH.

What is a normal testosterone concentration ?

Testosterone concentrations in the blood vary from patient to patient. They are at their highest between 8-10am and lowest at about 10pm. In Tayside the normal range for healthy men is usually between 10-35nmol/l.

What symptoms may I have of hypogonadism ?

Other symptoms or problems may develop in the long-term including:

What causes hypogonadism ?

Hypogonadism affects about 5 in every 1000 men.

PRIMARY Hypogonadism

This occurs when the testes fail to work, for which there are many causes:

SECONDARY Hypogonadism

This is when the testes are not being stimulated due to a problem in the brain (hypothalamus, pituitary)

What treatment is available for hypogonadism ?

Testosterone can be replaced in one of 4 ways. There are advantages and disadvantages of each.

1.      Primoteston muscular injections every 3-4 weeks.. Injections may be uncomfortable, and patients may experience a tail-off in the effect of testosterone just prior to the next injection. Lately injections lasting up to 3 months have become available (Decapeptyl SR and Nebido

2.      Testosterone skin patches. Skin irritation may be a problem, and a new area of non-hairy skin is required every day in a 7 day cycle. Some patients find them obtrusive. Testosterone concentrations in the blood however are more stable

3.      Testogel.  Applied to skin daily as a gel which is then absorbed over 24hrs.

4.      Restandol tablets - regrettably not sufficient for many sexually active men.

Are there side effects ?

The aim of treatment is to bring blood concentrations back to normal. Therefore there arenít usually many side-effects. Changes in mood, increased aggressive behaviour and increased sexual drive can be a problem

Other useful addresses

Klinefelters syndrome association
13 York Rise
Kent BR6 8PR
01689 870785

Where can I learn more?

Why not contact the Pituitary Foundation at;

PO Box 1944
Bristol, BS99 2UB.
Tel/Fax 0117 927 3355
e-mail- helpline@pitpat.demon.co.uk

Mens Health Help line
Tel: 0181 995 4448


NHS Tayside; 2006; version 1.0

Disclaimer; no liability whatsoever is accepted for information given and all such information, especially with regard to drug usage (UK version provided), must be checked with a personís health provider.