What total and free testosterone mean, why timing matters and the other markers a clinician looks at before recommending treatment.
By [AUTHOR NAME]Medically reviewed by [REVIEWER NAME, MD]Updated [7] min read
Key takeaways
Testosterone is highest in the morning, so tests are usually drawn early in the day.
Low testosterone is typically confirmed with two separate morning tests plus symptoms.
Free testosterone, SHBG, LH and FSH help explain why levels may be low.
Anyone on treatment needs ongoing lab monitoring.
Why does the time of a testosterone test matter?
Testosterone levels rise and fall through the day and tend to peak in the morning. That is why clinicians usually order a fasting blood test in the morning, and why a single low result is generally repeated before a diagnosis is made.
How do you read testosterone lab results?
Results are usually reported in nanograms per deciliter (ng/dL). Reference ranges vary by lab, and many clinical guidelines use about 300 ng/dL as a threshold for low total testosterone when symptoms are present.
Total testosterone: all testosterone in your blood, bound and unbound.
Free testosterone: the small portion not bound to proteins and available to tissues.
SHBG: a protein that binds testosterone and affects how much is free.
LH and FSH: signals from the brain that help show where the cause lies.
Do symptoms matter if my levels are normal?
A number alone does not make a diagnosis. Clinicians look at symptoms such as low libido, erectile changes, low energy or reduced muscle mass together with repeat lab results, and they may check for other causes like sleep problems, medications or thyroid issues.
How is testosterone therapy monitored?
If you start testosterone therapy, follow-up labs typically track testosterone levels, red blood cell count (hematocrit) and, depending on age, PSA. Testosterone therapy can also lower sperm production, so tell your clinician if you may want children.
When to talk to a clinician
Talk to a clinician before starting testosterone therapy or any product marketed to boost testosterone, and especially if you are trying to conceive or have a history of heart disease or prostate concerns.
Common questions
Reference ranges vary by lab, but many labs list roughly 300 to 1,000 ng/dL for adult men. A clinician interprets your result alongside symptoms and repeat testing.
Sources
American Urological Association. Evaluation and management of testosterone deficiency guideline. [ADD LINK]
The Endocrine Society. Testosterone therapy in men with hypogonadism clinical practice guideline. [ADD LINK]
U.S. Food and Drug Administration. Testosterone product labeling. [ADD LINK]
This article is for informational purposes only and is not medical advice. Talk to a licensed clinician before starting, stopping or changing any treatment.
