Laboratory test · Hormones and thyroid
Testosterone
- Sample: venous blood
- Preparation: morning after fasting; men 7–10 h
Test price
- Sample
- venous blood
- Preparation
- morning after fasting; men 7–10 h
Paymentcash, cards and instalments
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Testosterone is the main male sex hormone and is also produced in smaller amounts in women. This test measures total testosterone in blood. In men it is used for suspected testosterone deficiency, and in women for excessive hair growth, acne or irregular periods.
Who the test is for
- men with reduced sex drive, fewer morning erections or erectile dysfunction,
- men with infertility, smaller testicles or enlarged breasts (gynaecomastia),
- men with loss of muscle mass, osteoporosis or fractures after minor falls,
- boys with delayed puberty,
- men receiving testosterone treatment, to monitor therapy,
- women with excessive hair growth, acne, hair loss, irregular or absent periods and suspected polycystic ovary syndrome (PCOS).
What testosterone is and what the test indicates
In men, testosterone is mostly produced in the testicles, stimulated by the pituitary hormone LH. In women, the ovaries and adrenal glands produce it, and some is converted to estradiol. In men, testosterone affects sex drive and erections, sperm production, muscle mass and strength, bone density, fat distribution and red blood cell production.
Most blood testosterone is bound to proteins: tightly to SHBG (sex hormone-binding globulin) and more loosely to albumin. Only approximately 2 % is free. Total testosterone measures all testosterone together. When SHBG levels change, as often occurs in obesity, diabetes, older age and liver or thyroid disease, total testosterone can be misleading, so a doctor also requests free testosterone and SHBG.
In women, testosterone is measured more urgently if signs of increased male hormone activity develop suddenly.
Save with a panel
Test Testosterone is also included in these panels.
Preparation and sample
Testosterone is measured in venous blood. In men, it is highest in the morning and falls during the day. Therefore:
- come in the morning after fasting for 8 to 12 hours (water is allowed), because meals can temporarily lower testosterone;
- men should have blood taken between 7 and 10;
- avoid sampling during an acute illness such as a feverish infection, or after a sleepless night or exhausting exertion;
- if you take testosterone or other hormone preparations, tell your doctor and the laboratory, because sampling time depends on the preparation;
- if you take biotin (e.g. supplements for hair and nails), mention it at blood sampling;
- for women, cycle day is not crucial unless the doctor specifies otherwise.
How testosterone results are interpreted
The reference interval depends on sex, age and method and is printed on your report. A doctor interprets results alongside symptoms, age and other hormones.
Low testosterone in men
One low result is not enough for diagnosis. Guidelines confirm testosterone deficiency (hypogonadism) when symptoms are present and testosterone is low on at least two fasting morning measurements taken on different days. The European Association of Urology gives a cut-off of 12 nmol/L, and the American Endocrine Society approximately 9,2 nmol/L.
If deficiency is confirmed, a doctor investigates the cause. LH and FSH show whether the problem lies in the testicles or pituitary gland, and prolactinis also often measured. Testosterone is more often lowered by obesity and type 2 diabetes, sleep apnoea, serious chronic illness, some medicines (opioids, corticosteroids) and stopping anabolic steroids. Testosterone gradually falls with age; read more in Testosterone levels fall as men age.
High testosterone
In men, high testosterone most often results from taking testosterone or anabolic steroids. Total testosterone can also rise when SHBG is high, for example with an overactive thyroid or liver disease, while other causes are rare. In women, the most common cause is polycystic ovary syndrome. Less often it is an adrenal disorder, and very rarely an ovarian or adrenal tumour, suggested by very high levels and rapidly developing symptoms.
Total or free testosterone?
Total testosterone is usually sufficient for an initial assessment. If it is borderline or SHBG is abnormal, a doctor also requests free testosterone, for example in the Free Testosterone Panel, which includes total testosterone, SHBG and albumin. Broader hormonal assessment in men is available through the Male Sex Hormone Panel, and for women with suspected PCOS through the PCOS Panel.
How to arrange testing
You can have blood taken without an appointment or referral at one of our branches across Croatia (listed on the Contact page). Come in the morning after fasting; men should attend between 7 and 10. Prices for all tests and panels are available in the service price list.
Frequently asked questions
What is the difference between total and free testosterone?
Total testosterone includes all testosterone in blood, both bound and free. Free testosterone is the small portion not bound to proteins and acts directly on tissues. A doctor requests it when altered SHBG means total testosterone does not give an accurate picture.
Can testosterone also be measured in women?
Yes. Levels in women are much lower than in men, so results have their own reference interval. Testosterone in women is most often measured alongside other hormones to investigate excessive hair growth, acne or irregular cycles.
Are tests needed before testosterone therapy?
Yes. Before therapy, a doctor confirms deficiency with at least two fasting morning measurements and investigates the cause, usually also checking a blood count (haematocrit) and, in middle-aged and older men, PSA. These tests are also repeated during therapy.