Testosterone Blood Tests for Men: When to Test, What to Measure and Why Results Need Repeating

A reliable testosterone assessment is a sequence, not a one-off “male hormone panel”. It starts with symptoms and a correctly timed total testosterone test. If the result is low or does not fit the clinical picture, repeat and related tests help confirm the finding and identify its cause.

Testing broadly without a clinical question can create borderline abnormalities that do not explain how you feel. Testing too little can miss a treatable cause.

When is testosterone testing appropriate?

Testing is reasonable when a man has features such as reduced sexual desire, fewer spontaneous erections, erectile dysfunction, infertility, loss of body hair, low bone density, reduced muscle mass or other signs that create a genuine suspicion of hypogonadism.

Tiredness, low mood and poor concentration alone are not specific. They may still justify a wider health assessment, but a testosterone result should not distract from sleep, mental health, thyroid disease, anaemia, diabetes, medication and other possibilities.

Routine screening of every man without symptoms is not recommended.

How should the first test be taken?

For most men, total testosterone should be measured:

• fasting;
• in the morning, generally between 7am and 10am;
• after the usual main sleep period;
• when not acutely ill; and
• before starting any testosterone-containing treatment.

Tell the clinician about shift work, poor sleep, recent serious exercise, medication, supplements and any non-prescribed hormones. Do not stop prescribed treatment without advice.

Which blood tests might be used?

This is not a mandatory bundle. The clinician chooses tests that can change the diagnosis or plan.

Why does a low result need repeating?

Testosterone can be temporarily low after poor sleep, food, acute illness or major physiological stress. Day-to-day biological variation and laboratory variation also occur.

Current European guidance recommends confirming a total testosterone result below 12 nmol/L on at least two separate morning samples before treatment. If the first test was taken late in the day or during illness, the repeat is particularly important.

What do LH and FSH add?

The pituitary releases LH and FSH to stimulate the testes.

• Low testosterone with high LH or FSH suggests the testes are not responding adequately: primary hypogonadism.
• Low testosterone with low or inappropriately normal LH and FSH suggests reduced signalling from the pituitary or hypothalamus: secondary hypogonadism.

The second pattern may prompt a medication review, prolactin test and, in selected cases, pituitary imaging or specialist referral. Severe headache, new visual disturbance or other neurological symptoms should be assessed promptly.

When is calculated free testosterone helpful?

It is most useful when total testosterone is borderline, symptoms and total testosterone do not match, or SHBG is likely to be altered.

Low SHBG can occur with obesity and insulin resistance, making total testosterone appear low while calculated free testosterone is less affected. High SHBG can occur with age, liver or thyroid conditions and some medicines, potentially masking a lower free level.

The result is still part of a clinical assessment; it is not an independent diagnosis.

Are blood tests needed before and during treatment?

Yes. Before possible testosterone treatment, assessment commonly includes haematocrit, cardiovascular risk, fertility intentions and an appropriate prostate discussion. Blood pressure, sleep apnoea risk, urinary symptoms and thrombosis history may also matter.

Once treatment starts, symptoms, testosterone and haematocrit are commonly checked at around three, six and twelve months and then at least annually once stable. PSA follow-up depends on age, risk and the agreed pathway.

Common testing mistakes

• testing late in the day and treating the result as definitive;
• testing during an acute illness;
• starting treatment after one low value;
• ignoring SHBG in a borderline or discordant case;
• measuring many hormones but not taking a proper history;
• failing to ask about fertility;
• using supplements or non-prescribed hormones before the diagnostic process is complete; and
• failing to arrange follow-up for an abnormal result.