Markers · Hormones
A testosterone of 350, in range, and you don't feel like yourself. Total testosterone, read against the rest of you.
What total testosterone measures, what it does in the body, why it's tested, and the two ranges it's read against. Everything said about the marker here comes from Merlin's own biomarker catalogue.
What total testosterone is
Total testosterone measures the combined amount of bound and unbound testosterone circulating in the bloodstream, reflecting overall androgen status in both males and females. In men, it is the primary indicator of gonadal and adrenal androgen production, governing reproductive health, muscle mass, bone density, mood, and energy levels. Low levels may indicate hypogonadism or other endocrine disorders, while elevated levels can suggest conditions such as polycystic ovary syndrome (PCOS) in women or exogenous androgen use.
What it does in the body
Testosterone is the principal male sex hormone and an anabolic steroid produced primarily in the Leydig cells of the testes in men and in smaller amounts by the ovaries and adrenal glands in women. It drives development of secondary sexual characteristics, supports spermatogenesis and libido, promotes muscle protein synthesis and bone mineralization, regulates red blood cell production via erythropoietin stimulation, and influences mood, cognition, and metabolic function including insulin sensitivity.
Why it's tested
Total testosterone testing is used to diagnose hypogonadism, evaluate erectile dysfunction, assess libido and fertility concerns in men, investigate androgen excess (e.g., PCOS, adrenal tumors) in women, monitor testosterone replacement therapy, evaluate delayed or precocious puberty, and screen for pituitary or hypothalamic disorders affecting the HPG axis.
The two ranges
The reference range reflects population statistics. The target reflects physiology.
- Lab reference range
- Males (adult): 264-916 ng/dL; Females (adult): 10-82 ng/dL
- Functional target
- Males (adult): 500-900 ng/dL; Females (adult): 15-70 ng/dL
Those are different numbers, and you deserve to know which one you're looking at. Merlin reads your result against both.
Where this lives
A Field Guide to Low Testosterone & Hypogonadism
The field guide that covers total testosterone in depth, whole and public.
In a real read
The real read on this site is a Cardiovascular one, so there's no hormone panel in it. What it shows is the shape: one system, thought all the way through, with the score, the narrative and the layers underneath. A hormone panel gets one of these too, read against everything else you brought.
A real Cardiovascular surface from a real anonymized panel: the score, the narrative, the layers underneath. Yours will be built the same way, on your own numbers.
Educational context for your conversations with your licensed healthcare provider, not a diagnosis or a treatment plan. Merlin reads results; it doesn't diagnose.
No testosterone result yet? You can order it inside Merlin: it's on Complete Female ($670) and Complete Male ($745).
Bring the panel this number came from. Merlin reads it against everything else you have, every system and every year, then shows you what it means and what's worth finding out next. Start with your first month.