What testosterone level is low enough to need treatment?

Short answer

• Testosterone replacement is usually considered only for men who have BOTH (1) consistent symptoms of testosterone deficiency (low libido, erectile problems, low energy/mood, loss of muscle, increased body fat, anemia, low bone density) and (2) repeatedly low morning total testosterone.
• Most guideline groups use a total testosterone cutoff of about 300 ng/dL (≈10.4 nmol/L) as the threshold below which testosterone is considered low. Men with levels well below that (for example <200–250 ng/dL) are much more likely to have clinically important deficiency.

Details and practical steps

1. Measure correctly

• Obtain a morning (ideally 7–10 AM), fasting total testosterone. Illness, recent heavy exercise, and some medications can lower results.
• If the first test is low or borderline, repeat on a separate morning before diagnosing.

1. Numbers to keep in mind

• Total testosterone <300 ng/dL (≈10.4 nmol/L): commonly used threshold for low T in guidelines.
• 200–300 ng/dL: “borderline” — assessment of symptoms and measurement of free testosterone or SHBG may help.
• <200 ng/dL: more reliably associated with deficiency and symptoms.
• Lab reference ranges vary; always compare to the lab’s normal range and consider units (ng/dL vs nmol/L).

1. Free testosterone

• Free (or bioavailable) testosterone can be helpful when total T is borderline (200–350 ng/dL) or when SHBG is abnormal (older age, obesity, liver disease, some meds). Assays and cutoffs vary; use calculated free testosterone (Vermeulen) if available and interpret with the lab’s reference range.

1. Confirm cause and safety testing before treatment

• If low, clinicians usually measure LH/FSH to distinguish primary (testicular) vs secondary (pituitary/hypothalamic) hypogonadism, and check prolactin, hematocrit, and PSA as part of safety screening.
• Testosterone therapy is for symptomatic men with confirmed low levels — not for men with normal labs even if symptomatic, nor for men with low-normal levels without symptoms.

1. Risks/benefits and specialist referral

• Testosterone therapy has benefits (improved libido, muscle, mood, bone density in some men) and risks (erythrocytosis, possible effects on prostate, unclear cardiovascular risk). Discuss with your clinician; consider endocrinology or urology referral for complicated cases.

If you want, tell me your exact lab numbers (total testosterone, time of day, free testosterone or SHBG if available) plus your symptoms and age, and I can help interpret them.