Hormones
Testosteron
The main male sex hormone; measured in men when a deficiency is suspected, in women when an excess is suspected.
Everything about this testWhat it measures
In men, testosterone is made mainly in the testicles, controlled by LH from the pituitary gland; in women, the ovaries and adrenal glands make a small amount. The hormone is responsible for sex drive, muscle mass, bone strength, body hair and the production of sperm cells. This analysis measures total testosterone: the part bound to the proteins SHBG and albumin plus the small free part that is active. The value is highest in the morning and falls during the day.
- Testosterone deficiency (hypogonadism) in men, caused by the testicles themselves or by the control from the pituitary gland
- Too much male hormone in women, for example with polycystic ovary syndrome (PCOS)
- Suppression of the body's own production by anabolic steroids or testosterone treatment
High
In men, a raised testosterone is usually the result of testosterone treatment or anabolic steroids. Rarely: a tumor that makes testosterone. In women, a raised value often fits PCOS, with symptoms such as irregular menstruation, acne and excess hair growth. Markedly raised values in women are sometimes caused by a disorder of the adrenal glands or, rarely, a tumor of the ovary or adrenal gland. Note: the contraceptive pill and pregnancy raise the binding protein SHBG, which makes total testosterone look higher without there being more active hormone.
Low
In men, a low testosterone can point to a deficiency, with symptoms such as less interest in sex, erection problems, tiredness, less muscle strength and low mood. A single low value does not prove this yet: the value is lower in the afternoon, falls temporarily with illness, lack of sleep, overweight and stress, and varies from day to day. That is why, according to the Dutch GP guideline (NHG) on sexual problems and the guidance of the Dutch Society for Endocrinology (NVE), a low value is always repeated, in the morning, and assessed together with the symptoms. With use of anabolic steroids, the body's own production is often suppressed and the value stays low for months after stopping. In women, a low value has no clear meaning.
Preparation
- Preferably do not eat for 8 hours before the sample is taken and drink only water. Testosterone is temporarily lower after a meal.
- Have your blood taken in the morning before 11.00, because testosterone drops during the day. If you work nights, do not have your blood taken straight after a night shift.
- Do you take biotin (vitamin B8, often in hair and nail supplements)? Stop at least 2 days before the sample is taken, or 4 days for a high dose.
If your result is abnormal
With a low value, the GP repeats the measurement in the morning after a few weeks, usually together with SHBG, LH and FSH to see whether the cause lies in the testicles or in the pituitary gland. With two low values and symptoms, referral to an internist-endocrinologist or urologist follows. In women with a raised value, tests for PCOS usually follow.
Reliability
A total testosterone is a snapshot with a strong daily rhythm and considerable differences between laboratories. The result means the most with erection problems together with reduced interest in sex, measured before 11 in the morning; according to the Dutch GP guideline (NHG) on sexual problems, a low value is repeated after a few weeks. The guidance of the Dutch Society for Endocrinology (NVE) follows the same approach: the diagnosis of testosterone deficiency requires at least two low morning values and persistent symptoms. Only then is the cause investigated with LH, FSH and, if needed, SHBG and prolactin.
Limitations
- The timing: testosterone is highest in the early morning and clearly lower in the afternoon. Sample collection before 11 o'clock, preferably fasting, and not after a night shift or with jet lag.
- Temporary fall due to illness, fever, lack of sleep, heavy exercise shortly before the sample collection, alcohol, malnutrition and overweight.
- Medicines and substances: anabolic steroids, opioids, corticosteroids and some antidepressants and antiepileptics lower the value; the contraceptive pill and pregnancy raise total testosterone via SHBG.
- Reference values differ by laboratory, sex and age; in men with overweight or liver disease, total testosterone says less than the calculated free testosterone.
How common is this
Testosterone deficiency with symptoms is estimated to occur in 2 to 6 in 100 men over 40, more often at older ages and with overweight. A low value without symptoms is much more common and is not a disease in itself. In women, a raised testosterone is usually part of PCOS, a common condition in the childbearing years.
Who is this useful for
Useful for men with symptoms that fit testosterone deficiency, especially erection problems together with less interest in sex, and for men who have used anabolic steroids and want to know whether their own production is recovering. In women, useful with irregular or absent menstruation together with excess hair growth or acne. In healthy men without symptoms, a single value says little: a low value without symptoms is common and is no reason for treatment.
Downsides and risks
- A single low morning value is often explained online as a 'deficiency' and as a reason to use testosterone; without a repeat measurement and symptoms, this leads to unnecessary or harmful treatment.
- Testosterone from outside the body suppresses your own production and fertility; a result should therefore never lead to use on your own initiative.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results