You got your labs back. The reference ranges are wide. Some numbers are bolded as "out of range," some aren't. You have no idea what you're actually looking at. Here's the field guide.
Total Testosterone
The most-talked-about number, and the most misleading on its own. Lab reference ranges typically run 264-916 ng/dL for adult men, which is too wide to be useful. A 28-year-old with a Total T of 320 is technically "normal" but functionally low for his age.
What matters: where you fall in the range relative to your age, and how it compares to your previous results. Trends matter more than single readings.
Free Testosterone
The portion of testosterone that's actually biologically active. Most circulating testosterone is bound to proteins (mostly SHBG and albumin) and unavailable to your tissues. Free T is what's left over to actually do work.
Reference: roughly 50-220 pg/mL depending on assay. This is the number that correlates most directly with symptoms. A man with a normal Total T but low Free T can have full TRT-like symptoms.
SHBG (Sex Hormone Binding Globulin)
The protein that binds testosterone. High SHBG means less Free T even if Total T looks fine. Low SHBG can mean elevated Free T and a higher risk of estrogen issues.
SHBG is influenced by liver health, thyroid function, insulin sensitivity, and alcohol intake. Treating low T without understanding SHBG is treating the symptom, not the system.
Estradiol (E2)
Yes, men have estrogen, and they need some of it. Estradiol matters for bone density, mood, libido, and joint health. Too low is as bad as too high.
Optimal range for most men: 20-40 pg/mL (sensitive assay). On TRT, E2 often rises proportional to Total T — that's normal. The goal is the ratio, not the number.
LH and FSH
These are signals from your pituitary telling your testes to make testosterone (LH) and sperm (FSH). When they're high but testosterone is low, the issue is usually with the testes themselves (primary hypogonadism). When they're low alongside low testosterone, the issue is upstream — pituitary or hypothalamic.
This distinction changes treatment completely. A man with secondary hypogonadism has different options (clomiphene, hCG, lifestyle interventions) than one with primary.
The numbers a clinician actually wants
- Total T — drawn early morning (8-10am), fasted
- Free T — by equilibrium dialysis if possible (more accurate)
- SHBG
- Estradiol — sensitive assay, not standard
- LH and FSH
- Prolactin — rules out pituitary tumors
- TSH and Free T4 — thyroid drives a lot of the same symptoms
- Comprehensive metabolic panel + CBC + lipids + A1C + Vitamin D
The bottom line
One number out of context is meaningless. A full panel interpreted by someone who actually treats hormonal issues — not a generic primary-care annual — is what you need. If your provider only ordered Total T and called it a day, you've been short-changed.