Testosterone is measured with a blood test. A sample is taken, usually in the morning when levels are highest, and the laboratory reports your total testosterone in nanograms per decilitre (ng/dL). Most clinicians also measure free testosterone, because the total figure alone can be misleading.
Why testosterone has to be measured rather than guessed
The symptoms of low testosterone are real but they are not specific. Fatigue, weight gain, low libido, poor concentration and disturbed sleep are also caused by thyroid disorders, sleep apnoea, depression, diabetes and simple overwork.
That overlap is the reason testing exists. A blood test separates the men who have a hormonal problem from the men who have something else going on — and the second group are better served by finding out than by starting a treatment they do not need.
Why the test is usually done in the morning
Testosterone follows a daily rhythm. It is typically highest in the early morning and declines through the day, so a sample taken at 8am and one taken at 4pm can give noticeably different results from the same man on the same day.
For that reason testing is generally done in the morning, which gives a consistent basis for comparison and for any follow-up tests later.
What a testosterone blood test measures
A useful panel measures more than one figure:
- Total testosterone — everything circulating in your blood, bound and unbound
- Free testosterone — the unbound portion your body can actually use
- Estrogen — because testosterone converts to estrogen, and the balance matters
Most of the testosterone in your blood is bound to proteins, principally sex hormone binding globulin (SHBG) and albumin. While bound, it is unavailable to your body. This is why a man can have a total reading inside the normal range, high SHBG, very little free testosterone, and real symptoms.
If only total testosterone is measured, that man looks fine on paper. For more detail on what the figures mean, see our guide to normal testosterone levels.
What else is worth testing at the same time
Because several other conditions produce the same symptoms, a broader panel is more informative than testosterone alone. At Prime Men’s Health our at-home blood spot kit also measures insulin, blood lipids, Vitamin D, thyroid hormones and elements such as magnesium.
If your testosterone comes back normal, those additional markers often point to what is actually causing how you feel.
Do you need to visit a laboratory?
Not necessarily. Blood spot testing can be completed at home: you register the kit online, collect a small sample, allow it to dry, and post it back. No draw station, no appointment, no waiting room.
Results are typically available three to five days after the laboratory receives your sample, and a physician reviews them with you on a video visit. Our at-home lab kit costs $99.
What happens after the test
A number on its own does not decide treatment. A physician considers your total testosterone, your free testosterone, your age, your body size and the symptoms you are experiencing, together.
Two men with identical readings can need quite different care. One may have clear symptoms and benefit from treatment; the other may feel well and need nothing at all.
How often should testosterone be retested?
If you begin treatment, monitoring continues. Once your optimal levels are established you can expect lab work every six months. We also test PSA at baseline and every six months during therapy, to monitor prostate health.
Ongoing monitoring is not an optional extra. Any provider offering testosterone therapy without regular blood work is not managing it properly.
Getting tested
Testing starts with a free consultation, by phone or online. If testing is appropriate for you, a kit is sent to your home and a licensed physician reviews the results with you.
Call 1-800-530-7746 or book a free consultation.
Related reading
For independent information on this topic, see Cleveland Clinic guidance on low testosterone.
Medically reviewed by John Webb, MD, MBA. Dr. Webb completed a men’s health (Andrology) clinical research fellowship at Harvard Medical School and has nearly 20 years of experience in progressive healthcare leadership.
This article is general information and is not medical advice or a substitute for consultation, diagnosis or treatment by a licensed healthcare professional.