What testosterone level is low enough to need treatment?

Short answer: Most U.S. guidelines use a total testosterone of about 300 ng/dL (10.4 nmol/L) or lower — measured in the morning on at least two occasions — together with compatible symptoms, as the usual threshold to consider treatment.

Details and practical steps

• Threshold to consider treatment: The Endocrine Society and American Urological Association generally use total testosterone ≤300 ng/dL on two separate morning tests as the cutoff for “low” when symptoms are present. Very low values (for example <200–250 ng/dL) are much more clearly abnormal.
• Symptoms matter: Treatment is indicated based on both low lab values and consistent symptoms (low libido, erectile dysfunction, low energy, reduced muscle mass/strength, depressed mood, decreased bone density, anemia).
• When to do additional tests: If the total testosterone is borderline (roughly 250–400 ng/dL) or if you have conditions that alter sex‑hormone–binding globulin (SHBG) — obesity, liver disease, thyroid disease, age — measure free testosterone and SHBG and compare to your lab’s reference ranges. Labs use different assays and reference intervals, so always interpret results against the lab report.
• How to test: Blood should be drawn in the early morning (typically 7–10 AM) when testosterone is highest. Repeat the test on a separate day before making treatment decisions.
• Workup before treatment: Measure LH and FSH to distinguish primary (testicular) from secondary (pituitary/hypothalamic) hypogonadism; consider prolactin if LH/FSH low; screen for reversible causes (medications such as opioids or glucocorticoids, sleep apnea, obesity, uncontrolled diabetes).
• Risks, contraindications and monitoring: Testosterone therapy can help libido, strength, bone density and mood in men with deficiency, but it can cause erythrocytosis, worsen untreated sleep apnea, and is relatively contraindicated with active prostate or breast cancer. If treated, monitor hematocrit, PSA, testosterone level, and symptoms per guidelines.
• Fertility: Testosterone therapy suppresses sperm production. If you want to preserve or achieve fertility, discuss alternatives (clomiphene, hCG, referral to a reproductive/urology specialist) before starting treatment.

Next steps

• If you have symptoms and a recent morning total testosterone <300 ng/dL, discuss with your primary care doctor, urologist, or endocrinologist for repeat testing and a full evaluation.
• If you already have a lab result you want interpreted, tell me the value, units (ng/dL or nmol/L), and the time of draw and I can help interpret it in context.