How to Get a Testosterone Test and What to Expect

Getting a testosterone test is straightforward: you need a blood draw, ideally from a vein in your arm, performed in the morning while fasting. Most people start by asking their primary care doctor, who can order the test through a standard lab. What makes the process worth understanding, though, is everything that can quietly distort the result, from what time you show up to whether you ate breakfast, and the surprisingly large differences between laboratory methods.

Why the Morning Matters

Testosterone follows a daily rhythm, peaking in the early morning hours and declining as the day goes on. Clinical guidelines recommend having your blood drawn between about 7 and 11 a.m. to catch that peak. This is not just a suggestion for the sake of neatness. In a study comparing samples drawn within that window to samples drawn later, the morning group averaged roughly 412 ng/dL while the later group averaged about 368 ng/dL, a clinically meaningful gap that persisted even after adjusting for age and weight.¹ Separate research found that afternoon levels can drop by around 43 ng/dL compared to morning values, with the decline being steeper in people whose morning testosterone is higher to begin with.²

What this means practically: if you show up for a blood draw at 3 p.m. and your level comes back low, the result may not reflect your actual hormonal status. It might just reflect the time of day. For this reason, if your doctor suspects low testosterone, the test should always be a morning draw. Some clinics are flexible about scheduling, so you may need to specifically request an early appointment.

Fasting Before the Test

Eating before a testosterone test can temporarily push your levels down. In one study, men who consumed a glucose drink saw their testosterone drop by about 25% within two hours. The suppression did not bounce back during that window. Among men who started with normal testosterone, roughly 15% dipped into the technically “low” range after the glucose load alone.³ A follow-up study looking at mixed meals rather than pure glucose found a similar pattern: total and free testosterone dropped by about 15 to 17% an hour after eating.⁴

This creates a real diagnostic problem. If you eat a normal breakfast before your appointment and your testosterone comes back borderline, it is genuinely unclear whether the food pushed you below the threshold or whether your fasting level is truly low. That is why most endocrinologists recommend fasting for at least eight hours before the blood draw. Water, black coffee, and medications you take routinely are generally fine, but check with your doctor if you are unsure.

What Gets Measured

When you hear “testosterone test,” it usually means a total testosterone measurement. Total testosterone includes all of the hormone circulating in your blood: the small fraction that is floating freely, the portion loosely bound to a protein called albumin, and the larger portion tightly bound to sex hormone-binding globulin (SHBG). Only the free fraction and the albumin-bound fraction are biologically active, meaning they can actually enter cells and do something.

For most men getting an initial screening, total testosterone is the standard starting point. Free testosterone becomes relevant in specific situations, particularly when your total testosterone is borderline (just above or below the lower normal range) or when there is reason to suspect that your binding protein levels are unusual. Conditions like obesity, liver disease, aging, and thyroid disorders can all shift SHBG levels, which changes how much of your total testosterone is actually available to your body.⁵ Two men with identical total testosterone levels can have quite different free testosterone levels depending on their SHBG.

Free testosterone can be measured directly or calculated from total testosterone and SHBG using a formula. The calculated approach is more common and cheaper, though the formulas used are known to have some inaccuracies because they are based on imperfect models of how testosterone binds to SHBG. Still, they are generally considered clinically useful for most situations.⁵

Not All Lab Methods Give the Same Answer

This is one of the least-discussed but most important aspects of testosterone testing. The method your lab uses to measure the hormone can meaningfully change the number you get back. Most commercial labs use immunoassay platforms because they are fast and relatively inexpensive. The gold standard, however, is a technique called liquid chromatography-tandem mass spectrometry (LC-MS/MS), which directly identifies and measures the testosterone molecule rather than relying on antibody reactions that can cross-react with other substances.

The difference is not academic. A head-to-head comparison of one widely used commercial immunoassay against an LC-MS/MS method found that the immunoassay consistently underestimated testosterone above 100 ng/dL and showed unreliable positive biases below that level.⁶ Another comparison found that immunoassay values ran significantly higher than LC-MS/MS values, with the disagreement worst at low concentrations.⁷ A third study testing five separate immunoassays against LC-MS/MS found that none of them were sufficiently reliable when testosterone was low.⁸

Why does this matter to you? If your testosterone is in a borderline or low range and the lab used an immunoassay, the number could be off by enough to change whether you are diagnosed or not. You can ask your doctor which assay the lab uses, and if accuracy is a concern, request that your sample be run by LC-MS/MS. Larger reference labs increasingly offer it, and it is especially recommended for women and children, whose lower testosterone levels fall squarely in the range where immunoassays are least reliable.

The Blood Draw Itself

If you have had blood drawn before, a testosterone test is nothing new. A technician ties a tourniquet around your upper arm, cleans a spot on the inside of your elbow, and inserts a needle into a vein. The draw takes a few minutes. You will usually have a small bandage on your arm and can go about your day immediately afterward. Results typically come back within a few days, depending on the lab.

Some people are curious about saliva-based testosterone tests, which are marketed as a more convenient alternative. Saliva testing does correlate with free testosterone to a degree, particularly in men, where one study found a moderate correlation between salivary testosterone and serum free testosterone.⁹ But the correlation is weaker in women, and saliva testing is not standardized enough for clinical decision-making in most medical settings. If you are getting tested because you and your doctor are considering treatment, a blood draw is the way to go.

Where You Can Get Tested

The traditional path is through your doctor. A primary care physician, urologist, or endocrinologist can order a testosterone panel. Insurance typically covers the test when there is a clinical indication, such as symptoms of low testosterone (fatigue, reduced sex drive, erectile difficulties, mood changes) or a condition known to affect hormone levels.

Direct-to-consumer lab services also offer testosterone testing without a doctor’s referral. Companies let you order a test online, visit a nearby lab for the blood draw, and receive results electronically. This route can be convenient, but there are trade-offs. The reference ranges printed on the report are only as meaningful as the assay used to generate them, and variability between commercial kits can be substantial. One study found a high degree of between-kit variability when measuring total testosterone across commercially available platforms, with the inconsistency being greatest in samples with low levels.¹⁰ If you go the direct-to-consumer route, plan to bring the results to a doctor for interpretation rather than self-diagnosing based on where you fall relative to the lab’s printed range.

Why One Test Usually Is Not Enough

Testosterone fluctuates naturally from day to day and even hour to hour. Illness, a bad night of sleep, stress, intense exercise, and what you ate the day before can all shift the number. Because of this biological variation, clinical guidelines generally recommend confirming a low result with a second test on a separate day before making a diagnosis. A single low reading is not definitive.

When repeating the test, the same preparation rules apply: early morning, fasting, and ideally at the same lab using the same assay so the results are comparable. If your first result was borderline, the second test might also include free testosterone and SHBG to get a fuller picture.

Sleep, Exercise, and Other Factors That Can Skew Results

A full night of missed sleep can measurably lower your testosterone. A meta-analysis found that total sleep deprivation significantly reduced testosterone levels in men, while partial sleep restriction (getting a few hours instead of a full night) showed a smaller, less consistent effect.¹¹ A separate study confirmed that total sleep deprivation and restricting sleep to only the first half of the night both markedly decreased morning testosterone.¹² If you pulled an all-nighter or slept very poorly the night before your test, mention it to your doctor. It could explain an unexpectedly low result.

Heavy exercise is another confounding factor. Athletes and people who train intensely sometimes show suppressed testosterone levels, a phenomenon linked to low energy availability or excessive training load. These dips tend to be temporary and resolve when training volume or caloric intake is adjusted.¹³ If you are a serious endurance athlete with a low reading, it does not necessarily mean you have a hormonal disorder. It may mean your body is temporarily downregulating testosterone in response to energy demands. Context matters here, and a doctor familiar with exercise physiology can help sort this out.

Obesity, chronic illness, opioid medications, and corticosteroids can all lower testosterone as well. These are not just confounders that affect the test; they are genuine causes of low testosterone. But they do mean that a low level found on a screening test might improve if the underlying issue is addressed, which affects whether testosterone replacement therapy is the right first step.

Testing in Women

Testosterone testing is not just for men. Women produce testosterone too, in smaller quantities, and it plays a role in energy, mood, bone density, and sex drive. Testing may be ordered when a woman has symptoms of excess testosterone, such as acne, unusual hair growth, or irregular periods, which can point toward conditions like polycystic ovary syndrome (PCOS).

The challenge is that women’s testosterone levels are much lower, often falling in the range where standard immunoassays perform worst. For this reason, LC-MS/MS is especially important when testing women and children, since it avoids the exaggerated inaccuracies that immunoassays show at low concentrations.⁸ If your doctor orders a testosterone test for you and you are a woman, it is worth asking whether the lab uses mass spectrometry. A test result from an unreliable assay could lead to a missed diagnosis or an incorrect one.

Monitoring If You Are Already on Testosterone Therapy

If you are already receiving testosterone replacement, the testing rules change. The timing of your blood draw relative to your last dose matters as much as, or more than, the time of day. For men using transdermal testosterone gel, one study found that testosterone levels measured two hours after application were adequate in about 70% of patients, but by 23 hours after application, only about 37% still had levels in the desired range.¹⁴ That means drawing blood at the wrong point in your dosing cycle could make it look like your dose is working perfectly or failing completely, depending on when you show up.

For injectable testosterone, the same principle applies. Levels peak a day or two after injection and gradually fall until the next dose. Your doctor will typically want to check your level at a specific point in the injection cycle, often midway or just before the next dose, to see your trough level. Always confirm the timing with your prescribing doctor before going in for the draw.

Other Tests That Often Come Along for the Ride

A testosterone test rarely comes alone. When evaluating possible low testosterone, doctors commonly order additional blood work to understand the full picture. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) help distinguish between a problem originating in the testes and one originating in the brain’s signaling pathway. A prolactin level can flag a pituitary issue. A complete blood count is useful both as a baseline and because testosterone therapy can increase red blood cell production, which needs monitoring. SHBG, as mentioned, helps interpret whether the total testosterone reading reflects what is biologically available. Thyroid function tests may also be included, since thyroid problems can mimic or contribute to symptoms of low testosterone.

If you are starting testosterone replacement therapy, expect ongoing monitoring every few months initially. Beyond testosterone levels, your doctor will track your hematocrit (the percentage of red blood cells in your blood), liver function, and prostate-specific antigen (PSA) if you are a man over a certain age. These are safety checks, not optional extras. Testosterone therapy has real benefits for people who genuinely need it, but it also has risks that require surveillance.

Reference Ranges and What “Normal” Actually Means

One of the most confusing aspects of getting your results back is interpreting the reference range. Most labs list a “normal” range for adult men somewhere around 264 to 916 ng/dL, though the exact numbers vary by lab and by assay. These ranges are derived from populations of presumably healthy men, but they blend together 20-year-olds and 70-year-olds, lean and obese individuals, morning and afternoon draws. A 300 ng/dL result in a 25-year-old athlete means something different from a 300 ng/dL result in a 65-year-old man with diabetes, even though both might technically fall in the “normal” range.

For this reason, experts recommend interpreting the number in the context of symptoms, age, and overall health rather than treating the reference range as a pass-fail line. A man with a total testosterone of 280 ng/dL who feels fine and has no symptoms may not need treatment. A man at 350 ng/dL who is profoundly fatigued, losing muscle mass, and experiencing sexual dysfunction might, after confirming with a repeat test and checking free testosterone. The number alone does not tell the whole story. The best results come from working with a doctor who understands the nuances of the test and can weigh the number against everything else going on.