What your testosterone number is, and isn't, telling you
A single number on a blood panel is easy to fixate on. Here's how andrologists actually read testosterone results, and what men should ask for alongside the headline figure.
What to remember before reading on.
- 1Total testosterone alone is insufficient. Always request free T, SHBG and LH for context.
- 2Diurnal rhythm matters: measure before 10am, fasted, on a rested day.
- 3Reference ranges are population-wide. Your baseline is more useful than a single 'normal' band.
- 4Low T does not automatically mean infertility; intratesticular levels can remain adequate.
Total, free, and the 98% you don't notice
The testosterone in your bloodstream travels two ways. Most of it, roughly 98%, is bound to proteins, primarily sex hormone-binding globulin (SHBG) and albumin. The remaining fraction is free, biologically active testosterone. When men hear "low T," they're usually being told a total number. The more clinically relevant figure is often the free one.
Quick reference: adult total testosterone typically sits between 264–916 ng/dL. Calculated free testosterone runs 9–30 ng/dL. SHBG anchors the whole ratio at 18–54 nmol/L.
Why the HPTA axis matters
Testosterone doesn't exist in isolation. The hypothalamic-pituitary-testicular axis (HPTA) is a closed feedback loop. LH from the pituitary signals Leydig cells to produce T; FSH supports Sertoli cells and spermatogenesis. A low T with high LH tells a completely different story than a low T with low LH.
This is why a standalone testosterone number is roughly as useful as a car's speedometer without knowing which gear you're in. The Hormone Panel 01 reports all six markers together for a reason: individually they're suggestive; together they're diagnostic.
"A single testosterone reading is a photograph. What we actually want is the film."
— Dr. M. Hartmann
What to ask for
If you're ordering a test through your GP, insist on at least:
- Total testosterone — the headline figure, but interpret it against everything below.
- Free or calculated free testosterone — what tissues actually see.
- SHBG — tells you whether low total is a binding-protein artefact.
- LH and FSH — separate primary (testicular) from secondary (pituitary) causes.
- Prolactin and estradiol — cheap context that rules out common confounders.
A panel without LH and SHBG is roughly half a result. If a provider won't add them, find one who will, or run it at home.