Low Testosterone Blood Test: What Your Levels Mean

A low testosterone blood test measures how much testosterone is in your blood, usually as total testosterone in ng/dL. The American Urological Association uses a total testosterone level below 300 ng/dL as a reasonable cutoff for low testosterone, but only when it shows up on two separate early-morning tests and comes with symptoms.

This guide explains which labs are ordered, how to prepare, what the numbers mean, and why one low result is not a diagnosis. If you want to know what happens after a diagnosis, read how online TRT works or visit our testosterone replacement therapy page.

What tests check for low testosterone?

The main test is total testosterone. Clinicians often add other labs to understand why testosterone is low and to make sure treatment would be safe.

Test	What it shows
Total testosterone	All testosterone in the blood. The main screening test.
Free testosterone	The portion not bound to proteins. Useful when total testosterone is borderline or SHBG is abnormal.
SHBG	Sex hormone binding globulin, the protein that carries testosterone. It changes with age, weight, and thyroid or liver problems.
LH and FSH	Brain signals to the testes. They help show whether the cause is in the testes or the pituitary gland.
Prolactin	Checked when LH is low or normal, to look for a pituitary cause.
Hematocrit or CBC	Red blood cell level. A baseline matters because testosterone can raise it.
PSA	A prostate marker, checked in age-appropriate men before treatment.

When should you get a testosterone blood test?

Testosterone is highest in the morning and drops during the day. Guidelines recommend drawing blood early in the morning, generally before 10 a.m. Recent illness, poor sleep, heavy exercise, and some medicines such as opioids or steroids can lower results. Some labs and clinicians also prefer fasting, since a meal can lower testosterone for a short time.

• Book a morning draw, ideally before 10 a.m.
• Avoid testing while sick or right after a night of poor sleep.
• Bring a full list of your medicines and supplements.
• Ask whether your clinician wants you fasting.
• Plan for a second confirming test on a different day.

What is a normal testosterone level for men?

Lab reference ranges vary, but many use a range of roughly 264 to 916 ng/dL for adult men. That range comes from a standardized study of healthy young men and is used by the Endocrine Society. The AUA uses 300 ng/dL as its cutoff for low testosterone. A number just under a cutoff does not automatically mean you need treatment. Symptoms, repeat results, and the cause all matter.

Why do you need two tests to diagnose low testosterone?

Testosterone varies from day to day. In studies, a meaningful share of men with one low result had a normal level when retested. That is why both the AUA and the Endocrine Society call for two separate low morning results before diagnosing testosterone deficiency. A program that prescribes after one test, or with no test at all, is not following the guidelines.

What symptoms go along with low testosterone?

Labs alone are not enough. Clinicians look for symptoms such as low sex drive, erectile problems, fatigue, low mood, reduced muscle mass, and loss of body hair. Many of these have other causes, including poor sleep, depression, thyroid problems, and weight gain, so a good evaluation looks at the whole picture.

What happens after a low result?

If two morning tests are low and you have symptoms, your clinician looks for a cause and talks through options. Those can include lifestyle changes, treating an underlying condition, or testosterone therapy. If you want children soon, say so early, because testosterone therapy can lower sperm production. See how it works to learn how a StemVera visit is set up.

Bottom line

A low testosterone diagnosis needs symptoms plus two separate low morning blood tests, not a single number. Knowing which labs are ordered and how to prepare helps you get an accurate answer. Explore our hormone therapy options when you are ready to talk to a clinician.