Testosterone & TRT lab interpreter
Paste in your testosterone-panel numbers and see each one read against adult-male reference ranges and the clinical thresholds the guidelines actually use — including the 54% hematocrit action threshold that drives most TRT dose changes. It explains the why, not just a red or green light. Educational — never a diagnosis.
Reading
Enter one or more lab values on the left. Each is classified against widely-used adult-male reference ranges and the clinical action thresholds from the major guidelines — with the reasoning behind it.
Total testosterone reference by age (ng/dL)
| Age | Typical range | Visual |
|---|---|---|
| 19–29 | 264–916 | |
| 30–39 | 251–870 | |
| 40–49 | 230–800 | |
| 50–59 | 215–740 | |
| 60–69 | 196–680 | |
| 70+ | 156–620 |
The 264–916 ng/dL harmonized range is anchored to healthy non-obese men 19–39 (Travison 2017); ranges drift downward with age and are illustrative. Always compare against your own lab’s reference interval.
How to read these labs together
A testosterone panel only makes sense as a set. Total testosterone is the headline number, but most of it is bound and inactive; SHBG decides how much is free, so a normal total with high SHBG can still mean low free testosterone. On therapy, the lab that most often forces a change isn’t a testosterone value at all — it’s hematocrit, which testosterone (especially injectable) pushes up; the Endocrine Society sets the action point at 54% (Bhasin 2018). Estradiol rises with dose and usually doesn’t need “fixing,” while PSA is a prostate-safety check where a confirmed rapid rise matters more than the absolute number. The harmonized total-T reference (264–916 ng/dL) comes from Travison 2017.
For the deeper background, see testosterone levels by age, TRT and hematocrit, TRT side effects, and anastrozole for men. To estimate free testosterone from total T and SHBG, use the testosterone calculator.
Common questions
- What hematocrit is too high on TRT?
- The Endocrine Society guideline uses a hematocrit of 54% as the action threshold: at or above it, the advice is to evaluate, reduce or pause testosterone, and consider therapeutic phlebotomy. Testosterone — especially injectable forms — raises red-cell mass, so a rising hematocrit is the single most common reason to adjust a TRT dose, and it's the key lab to track over time. Values in the low-50s but under 54% are common and usually managed by rechecking and watching the trend.
- What is a normal testosterone level?
- The CDC-harmonized reference range for total testosterone in healthy non-obese men aged 19–39 is 264–916 ng/dL (about 9.2–31.8 nmol/L). The AUA uses 300 ng/dL as the threshold below which testosterone deficiency is considered. Ranges drift downward with age and are assay-specific, so always compare against your own lab's reference interval — and remember a single value is never a diagnosis. Low testosterone is diagnosed from symptoms plus consistently low values on repeat morning tests.
- Why is my total testosterone normal but free testosterone low?
- Because most testosterone in blood is bound — tightly to SHBG and loosely to albumin — and only the free (and bioavailable) fraction is active. When SHBG is high, more of your total testosterone is locked up, so total T can read 'normal' while free T is low. That's why the interpreter flags SHBG alongside total and free T: the three only make sense together. To estimate free T from total T and SHBG, use our free-testosterone calculator.
- Should I take an aromatase inhibitor if my estradiol is high on TRT?
- Usually no. Estradiol rises with testosterone dose, and modest elevations in men are generally not harmful — estradiol is essential for male bone density and libido. Routine use of an aromatase inhibitor like anastrozole to 'lower estrogen' on TRT is largely unsupported and risks over-suppressing the estradiol your bones need. High estradiol with symptoms (e.g. gynecomastia) is a conversation for your clinician, not a reason to self-treat.
- Is this lab interpreter a diagnosis?
- No. It classifies values against widely-used adult-male reference ranges and published guideline thresholds, and explains what each means — but reference ranges are assay- and lab-specific, a single value is never diagnostic, and management belongs with a clinician who can see your full picture. Treat the output as a way to understand your panel before a conversation with your provider, not as medical advice.