Testosterone, total
HormonesAlso known as: total T, serum testosterone, TT, male sex hormone
The primary male sex hormone responsible for sexual development, sperm production, muscle mass maintenance, bone density, and overall energy levels.
Low levels can cause fatigue, reduced libido, erectile dysfunction, decreased muscle mass, and mood changes. Age-related decline is normal, but significant deficiency may warrant supplementation.
Why this matters
Total testosterone levels reveal overall androgen status and help identify hormonal imbalances. Low levels can affect energy, muscle mass, bone density, and libido, while high levels may indicate endocrine disorders. Maintaining a healthy lifestyle including exercise, balanced diet, and sleep supports normal testosterone levels and overall hormonal health.
How this connects to other biomarkers
- Low total Testosterone with low Sex hormone-binding globulin (SHBG) and high HOMA-Index suggests obesity-related low testosterone; treating insulin resistance often improves testosterone.
- Low total Testosterone with elevated Luteinizing hormone (Lutropin) and FSH, Follitropin indicates the testicles themselves are failing (primary hypogonadism); low LH/FSH suggests the brain/pituitary is the problem (secondary hypogonadism).
- The Free Androgen Index (FAI) and direct Testosteron, free measurements correct for SHBG-driven discordance between total and biologically active testosterone.
How often should I test Testosterone, total?
Most adult men benefit from yearly total testosterone testing from their 30s onwards, drawn in the morning between 7 and 10 AM when levels peak. If you start or adjust testosterone therapy, retest at 6 to 12 weeks to confirm response, then every 6 to 12 months once stable.
At baseline / for screening: Once every 12 months from age 30 as part of a hormone panel, drawn in the morning between 7 and 10 AM when testosterone peaks.
When monitoring an intervention or change: Retest 6 to 12 weeks after starting or adjusting testosterone replacement therapy (gel, injection, pellet) to confirm you've reached the target range. Once stable on a dose, retest every 6 to 12 months. After meaningful body composition changes (weight loss, training, sleep improvement), expect 3 to 6 months for natural testosterone to shift.
Note: Testosterone peaks in the morning (7 to 10 AM) and falls 20 to 30 percent by afternoon. Standardize timing across draws; after acute illness or poor sleep, wait 2 to 4 weeks for recovery before retesting.
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