How to Test Your Testosterone Properly (and the 3 Things Doctors Skip)
6 min read
Most men who finally get their testosterone tested walk away with a number that's either wrong, incomplete, or impossible to interpret. Then they make a decision — start treatment, or give up — based on it.
You can do better than that, and it costs nothing but knowing what to ask for. Here's how to get a testosterone result you can actually trust.
1. Test in the morning — before 10am
This is the single most skipped step, and it invalidates a huge share of "low testosterone" diagnoses.
Testosterone follows a daily rhythm. It peaks in the early morning and falls through the day. In men aged 30–40, levels measured at 4pm run roughly 20–25% lower than the same man at 8am. Test in the afternoon and a perfectly normal man can look deficient.
The major clinical guidelines exist for exactly this reason: the Endocrine Society and the AUA both say testosterone should be measured in a morning blood draw, and not after 10am.
If a clinic tests you at 2pm and tells you you're low — that's not a diagnosis, that's a scheduling error. Get it done in the morning.
2. Test twice, and test fasted
One reading is a data point. Two agreeing readings are a fact.
Testosterone varies enough day to day that a single low result can be a fluke. Any competent clinician will want two separate morning draws — usually a week or two apart — both below range, before treating you for anything.
Test fasted, too. Eating, especially carbohydrate, transiently lowers testosterone. And don't test while you're acutely ill, hungover, or right after a brutal training block — all three temporarily depress the result and none of them reflect your real baseline.
3. Ask for the full panel — including the two markers doctors skip
This is where most men get short-changed. A basic order comes back with a single "total testosterone" number and nothing to make sense of it.
Ask for all of this:
- Total testosterone — the headline number.
- Free testosterone — the fraction actually available to your tissues, and often the more useful one. A man can have a "normal" total and low free.
- SHBG — the protein that binds testosterone. It explains mismatches between total and free.
- LH and FSH — the two your doctor probably won't order, and the most informative on the whole panel.
That last pair is the one that matters most, so it's worth understanding why.
LH is the signal your brain sends to tell your testes to make testosterone. Reading it alongside your testosterone tells you where a problem actually is:
- Low testosterone with high LH → your brain is shouting and your testes aren't responding. The problem is in the testes (primary).
- Low testosterone with low or normal LH → the signal itself is weak. The problem is upstream, in the brain's signalling — and this is the pattern that sleep, weight, alcohol, and stress produce.
Those two situations have completely different answers. Ordering testosterone without LH and FSH is like being told your car won't start without checking whether it's the battery or the engine. Most men are never offered it.
What the numbers roughly mean
Reference ranges vary by lab, but as a rough guide, most labs put total testosterone somewhere around 300–1000 ng/dL. Below ~300 on two morning tests, with symptoms, is the range where clinicians start talking about treatment.
But "in range" and "optimal for you" aren't the same thing, and a number on its own doesn't diagnose anything. Symptoms plus two properly-timed tests plus LH/FSH — read by a clinician — is what actually tells the story. Anyone treating you off one afternoon number is cutting corners.
If your doctor won't test you
A common frustration: you ask, and your GP says "you're normal for your age," or refuses to order free testosterone, or won't test at all.
You're allowed to advocate for yourself. Ask specifically for a morning total and free testosterone, SHBG, LH and FSH. If they still won't, that's a reasonable moment to seek a second opinion or a direct-to-consumer lab. Just make sure whoever you go to tests properly — plenty of clinics will happily skip straight to selling you testosterone after a single questionnaire, which is the opposite of what you want.
When it isn't testosterone at all
Worth saying plainly, because it saves a lot of men time and money: the symptoms people blame on low testosterone — fatigue, low drive, low mood, brain fog — are also caused by poor sleep, excess weight, heavy drinking, thyroid problems, anemia, vitamin D deficiency, and depression. All of those are more common than genuine hypogonadism, and most get missed when a man jumps straight to hormones.
If your mood is the loudest symptom, a doctor is a better first stop than a hormone clinic. And if your lifestyle has some obvious holes in it, fixing those first can move your levels enough that you never needed treatment.
Worth reading next: Is it low testosterone, or just your lifestyle? — how to tell whether your symptoms point at your hormones or at something more fixable.
Before you spend anything
If you're not sure it's even worth getting tested — or whether your symptoms actually point at testosterone versus something more fixable — that's exactly what our free assessment is for. It takes three minutes, asks for no email to see your result, and one of the answers it can give you is "this probably isn't testosterone, don't spend money on it."
We don't sell testosterone, supplements, or lab tests. We just help you get a straight answer — which is why we can tell you to test properly, or not to bother.
Educational information only. This is not medical advice and not a substitute for a licensed clinician. Reference ranges and interpretation vary; discuss your results with a doctor.
Sources: Diurnal variation and morning-testing guidance — Endocrine Society / AUA clinical guidelines; LH/FSH interpretation of primary vs secondary hypogonadism — Merck Manual, Male Hypogonadism.