Testosterone Interpretation Calculator
Interpret a total testosterone result alongside SHBG and albumin to estimate free and bioavailable testosterone using the Vermeulen method — often more informative than the total alone.
Formula & Reference
| Variable | Symbol | Formula | Units |
|---|---|---|---|
| Testosterone Interpretation Calculator | — | Free T estimated from total T, SHBG, and albumin (Vermeulen) | ng/dL and % |
Step-by-Step Examples
Total 520 ng/dL, SHBG 32 nmol/L, albumin 4.4 g/dL, morning sample.
- Total 520 ng/dL sits comfortably in range
- SHBG 32 is mid-range
- Free testosterone calculates to roughly 2% of total
- Both total and free are unremarkable
Total 410 ng/dL, SHBG 78 nmol/L, albumin 4.2 g/dL.
- Total 410 ng/dL looks acceptable
- But SHBG 78 is markedly elevated
- Most testosterone is tightly bound and biologically unavailable
- Free testosterone falls well below expectation from the total
Total 240 ng/dL, SHBG 14 nmol/L, albumin 4.5 g/dL.
- Total is below the lower reference limit
- But SHBG 14 is low, so a larger fraction is unbound
- Free testosterone is proportionally higher than the total suggests
- Low SHBG is often seen with obesity and insulin resistance
Real-World Applications
Common Mistakes to Avoid
Guidelines require at least two separate early morning fasting measurements alongside consistent clinical symptoms. Single values vary substantially.
A normal total with high SHBG can mean genuinely low free testosterone, and a low total with low SHBG can mean adequate free testosterone. The total alone can point the wrong way.
Acute illness, recent surgery, sleep deprivation, and significant stress all transiently suppress testosterone. Results taken then do not reflect baseline.