How to read a testosterone blood test

This guide covers initial testing in adult men and other adults being evaluated for male hypogonadism. Tests ordered for other hormonal questions, or to monitor hormone treatment, need different context.

What does a testosterone blood test measure?

A blood test may report total testosterone, free testosterone, or both. Total includes testosterone attached to blood proteins and the unattached portion; free measures that unattached portion. Total is usually the starting test, and a free result adds information in selected situations rather than replacing it, as MedlinePlus explains.

Before searching the number, save the complete report. A cropped screenshot can leave out the units or the laboratory's range, which are essential to understanding what the number means.

How do I read the result, units and range?

Read the number, units and laboratory range together. A reference range describes a comparison population, not your personal target; different methods and populations can produce different ranges. A result within range does not rule out every health problem, as MedlinePlus explains.

A published example: a 2017 study established a total-testosterone range of 264–916 ng/dL (about 9.2–31.8 nmol/L) in healthy, nonobese men aged 19–39 from US and European cohorts, after calibration to a CDC reference method. It is a range for that population and standardized testing, not a chart for every age or laboratory. Travison and colleagues, 2017.

There is no universal “normal for your decade” or “optimal” testosterone chart. Age-specific ranges depend on the population and measurement method, as Endotext explains; use the range and age category on your own report. To convert testosterone from ng/dL to nmol/L, multiply by 0.0347; the converted figures here are rounded.

Keep these details together:

• Test name: total testosterone and free testosterone are different measurements.
• Result and units: copy both, such as ng/dL, rather than a number alone.
• Reference range: use the one printed on that report.
• Collection details: note the date, time, and whether you followed the preparation instructions.

What does a low result mean?

The AUA uses total testosterone below 300 ng/dL (about 10.4 nmol/L) as a cutoff supporting a diagnosis, alongside symptoms or signs and two early-morning measurements. This is a clinical decision threshold, not a universal boundary between feeling well and unwell or a treatment target.

A useful question is: “Does this result, measured this way, help explain what I am experiencing?” Low energy, reduced sexual desire, and low mood can have several causes. The 2026 Endocrine Society statement cautions that symptoms alone cannot diagnose hypogonadism.

Why test in the morning and repeat the result?

Diagnostic testosterone testing is commonly done around 7–10 a.m., when levels are generally higher, according to MedlinePlus. A low result needs confirmation on a separate morning; the AUA recommendation specifies separate occasions, not a mandatory number of days between them. Ask the ordering clinician when to repeat, especially after illness or if you work nights.

Using the same laboratory and measurement method can make repeat results easier to compare, as the AUA guideline recommends. Bring both reports to the follow-up, even if one is marked normal.

Do I need to fast? What about coffee or water?

The Endocrine Society recommends fasting for diagnostic morning testing; confirm your own preparation instructions. When fasting is requested, MedlinePlus says the usual duration is 8–12 hours, with plain water only, not coffee or other drinks. The ordering clinician sets the exact duration for the tests ordered, so this is not a universal rule for every blood draw.

Recent severe illness, poor nutrition, excessive exercise and some medicines can temporarily lower testosterone. Tell the clinician about illness, prescribed medicines, supplements and hormones so they can decide whether this is a suitable time to test. Endocrine Society: hypogonadism in men. Ask how to handle medicines and do not stop them on your own; if you ate or drank outside the instructions, tell the lab.

What should I ask at follow-up?

Ask whether the low result is confirmed and what might explain it. Depending on your history, a clinician may test luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to distinguish a problem in the testes from a problem in the signals controlling them. ARUP Consult describes that evaluation; further tests depend on the findings.

For the appointment, write down what changed, when it started, and what you want help with. Then ask: “Do I need a repeat test? Is free testosterone relevant here? What else could explain these symptoms?” These questions turn a flagged number into a more useful conversation. This guide cannot interpret your individual result or decide whether treatment is appropriate.

If treatment is being discussed, see our questions to ask before testosterone treatment.

Use the printable appointment checklist to keep your reports and questions together.