How to Read Testosterone Lab Results
Medically reviewed by Dr. Michael Koehler, MD | Affinity Whole Health
You got your bloodwork back and there's a sheet full of numbers and abbreviations that might as well be in another language. Total testosterone, free testosterone, SHBG, maybe estradiol and hematocrit. Some flagged, some not. What does any of it mean for how you actually feel?
You're not alone. A lot of men get dismissed by their primary care doctor because one number falls in the "normal range," even though they feel anything but normal. This guide breaks down what each marker means and how to have a more informed conversation with your provider.
If you're still trying to figure out which labs you need before starting testosterone therapy, we covered that in our Essential Labs for Testosterone Therapy guide. This post picks up where that one leaves off: you've got your results in hand, and now you want to understand what the numbers mean.
Total Testosterone: The Starting Point
The American Urological Association typical reference range for adult men is 300 to 1,000 ng/dL. Most labs flag anything below 300 as low, and that's the cutoff many providers use.
But "normal" and "optimal" aren't the same thing. A 40-year-old at 310 ng/dL is technically in range, but that level is more consistent with what you'd see in an 80-year-old. Mean testosterone declines by roughly 0.3-0.4% per year after age 30, and reference ranges vary substantially depending on lab method and population.
Timing matters. Testosterone levels peak in the morning, so morning draws (ideally 8-10 AM) give the most reliable baseline. If you're already on injectable testosterone, when in your dosing cycle the blood was drawn changes the number: a mid-cycle draw shows a steadier level, while a draw just before your next injection captures the trough. Always check with your provider about when to time your recheck.
Free Testosterone: The Number That Matters Most
Only about 1-3% of your testosterone is actually free — unbound and available for your body to use. The rest is bound to sex hormone-binding globulin (SHBG) or albumin. Free testosterone is what enters your cells and drives energy, libido, muscle recovery, mood, and cognitive function.
The European Male Ageing Study — over 3,000 men aged 40-79 — found that men with normal total testosterone but low free testosterone reported significantly more hypogonadal symptoms (ED, low libido, reduced morning erections, fatigue, weakness) than men with normal levels of both. Men with low total T but normal free T had symptom levels similar to healthy controls. At Affinity Whole Health, we always test free testosterone alongside total testosterone.
Reference ranges vary, but a commonly cited range for adult men is 5 to 21 ng/dL (or 50-210 pg/mL). Values below 5 ng/dL may suggest clinical deficiency.
SHBG: The Binding Protein That Can Fool Your Labs
SHBG binds tightly to testosterone in the bloodstream. The more SHBG you have, the more testosterone gets locked up and unavailable. This matters because SHBG can make your total testosterone look higher than it functionally is — your total T might read 500 ng/dL while your free T is low enough to cause symptoms.
Normal SHBG range is roughly 10 to 50 nmol/L. Aging, hyperthyroidism, liver disease, and low body weight raise SHBG. Obesity, insulin resistance, and hypothyroidism lower it. A 2020 retrospective review found SHBG below 30 nmol/L in 73% of men presenting for evaluation of adult-onset hypogonadism, inversely proportional to BMI.
Practical takeaway: if you carry extra weight, your SHBG may be low, making total T look lower than it functionally is. If you're lean and active with high SHBG, total T may look fine while free T is tanking. SHBG, total T, and free T always need to be interpreted together.
Estradiol (E2)
Men produce estradiol too — a portion of testosterone gets converted to estradiol by aromatase, which is concentrated in fat tissue. Estradiol plays roles in bone density, joint health, cardiovascular function, and sexual health. Both too high and too low cause problems.
High estradiol: water retention, bloating, mood swings, breast tenderness or gynecomastia, reduced libido.
Low estradiol: joint pain, low libido, fatigue, bone loss, ED.
A typical range on the sensitive assay is 20 to 40 pg/mL. Always request the sensitive estradiol test for male patients — standard assays are designed for female ranges and less accurate at male levels. If you're on TRT, your provider should be monitoring estradiol and may use medications like anastrozole to keep it in range. More on this in our estrogen management on TRT post.
Hematocrit, Hemoglobin, and PSA
Testosterone stimulates red blood cell production. Generally good — but if it goes too high, your blood becomes thicker (erythrocytosis), which is one of the most important safety markers monitored during TRT.
Hematocrit normal range is roughly 38-50%. Most TRT providers use 54% as the intervention threshold — the same threshold used in the TRAVERSE trial, the largest randomized study of testosterone safety to date. Hemoglobin runs 13.5-17.5 g/dL. If your hematocrit creeps above 50% on TRT, it's not a reason to panic, but it is a reason to talk to your provider. More in our guide on erythrocytosis and TRT.
PSA is generally under 4.0 ng/mL, though ranges vary by age. A sudden significant jump is what triggers concern, not a modestly elevated stable number. The TRAVERSE trial — a randomized, placebo-controlled study of 5,246 men on testosterone therapy — found no increase in prostate cancer or prostate-related events versus placebo over a mean of 27 months. This aligns with work by Dr. Abraham Morgentaler at Harvard, whose Morgentaler Method Fellowship Dr. Koehler completed. Monitoring PSA remains standard practice regardless.
LH and FSH
LH and FSH are pituitary hormones that signal the testes to produce testosterone and sperm. They help distinguish primary hypogonadism (testicular issue — high LH/FSH with low T) from secondary hypogonadism (pituitary or hypothalamic issue — low or normal LH/FSH with low T). On exogenous TRT, LH and FSH are typically suppressed — expected and normal, though this is also why sperm production decreases on TRT.
Other Markers on Your Panel
A comprehensive TRT panel also includes markers that aren't directly testosterone-specific but matter for safety and overall health:
CMP (comprehensive metabolic panel): checks liver and kidney function, blood sugar, and electrolytes — a general safety baseline.
Lipid panel: assesses cardiovascular risk. TRAVERSE found testosterone therapy slightly lowered total, LDL, and HDL cholesterol without raising heart-attack risk.
CBC (complete blood count): captures hematocrit and hemoglobin along with white cell and platelet counts.
Most TRT providers recheck these every 3-6 months during ongoing therapy — same cadence for your hormone levels. If something trends the wrong way, catching it early is far easier than reacting after the fact.
Putting It All Together
The most important thing to remember: no single number tells the whole story. Your provider needs to look at all markers together, in the context of your symptoms, age, body composition, and medical history.
A good mental model:
If your total T is low but your free T is in range — and you feel fine — you probably don't have a testosterone problem.
If your total T is "normal" but your free T is low — and you feel like garbage — you may well have a testosterone problem, and SHBG is probably the reason.
If both total and free T are low — and you feel it — that's the pattern that most clearly points toward testosterone therapy.
If your hematocrit, estradiol, or PSA trends unfavorably on TRT, that's a dose or protocol question, not a reason to stop therapy outright.
"Normal" ranges are population averages that include men of all ages and body compositions. A value in the bottom 10% is technically normal but may not be optimal for how you feel.
Frequently Asked Questions
What is a normal testosterone level?
The American Urological Association typical reference range for adult men is 300 to 1,000 ng/dL for total testosterone. Most labs flag anything below 300 as low. But "normal" and "optimal" aren't the same — a 40-year-old at 310 is technically in range, but that level is more typical of an 80-year-old.
What's the difference between total and free testosterone?
Total testosterone measures all the testosterone in your blood, including what's bound to proteins. Free testosterone is the 1-3% that's unbound and available for your body to use. Free testosterone is often the better indicator of how you actually feel — men with low free T report significantly more symptoms, even when total T looks fine.
What is SHBG and why does it matter?
SHBG (sex hormone-binding globulin) is a protein that binds to testosterone in the bloodstream. High SHBG locks up testosterone and makes it unavailable. Your total T might look normal while free T is low. Low SHBG (common with obesity and insulin resistance) can make total T look lower than it functionally is.
Does testosterone therapy increase my prostate cancer risk?
The TRAVERSE trial — the largest randomized study of testosterone safety, with 5,246 men — found no increase in prostate cancer or prostate-related events versus placebo. This matches decades of work by Dr. Abraham Morgentaler and others showing the old fear was based on flawed assumptions. PSA monitoring remains standard practice, but a stable modestly elevated PSA is very different from a sudden significant jump — the latter is what warrants further evaluation.
What to Do Next
At Affinity Whole Health, we run comprehensive panels that include all the markers above. Our Medical Director, Dr. Michael Koehler, MD, completed the Morgentaler Method Fellowship at Harvard and brings over 12 years of specialized experience to every patient consultation.
We've helped nearly 10,000 patients since 2012, with programs starting at under $299/month — all-inclusive pricing covering medication, supplies, shipping, follow-up labs, and provider consultations.
Disclaimer: This article is for educational purposes only and is not intended as medical advice, diagnosis, or treatment. Compounded medications from Affinity Whole Health are prepared in FDA-registered compounding facilities and are not FDA-approved drugs. All prescriptions require a provider consultation and lab work. Always consult a licensed healthcare provider before medications or treatment plans. Individual results vary.
Affinity Whole Health does not offer paid trials.