How to measure testosterone accurately in men

If you want real answers about your energy, strength, or sex drive, you need to know exactly how to measure testosterone — and which tests are worth your time and money.

Most guys search for “how to measure testosterone” because something feels off — less drive in the gym, fading morning erections, or energy that crashes by midafternoon. Guessing is easy. Getting reliable numbers is harder.

There are plenty of options: home kits that use saliva or urine, test strips, or full lab panels ordered by a doctor. They are not all created equal. Some methods give you noisy data that can push you toward the wrong conclusion, or even toward testosterone replacement therapy (TRT) you may not need.

Modern guidelines from urology and endocrine societies are very clear on one thing: testosterone should be measured in blood, in the morning, using validated techniques, and confirmed on at least two separate days before you label yourself “low T.”^[1],[2]

The relationship

Testosterone is the main male sex hormone. It is produced mostly in the testicles and helps control muscle mass, fat distribution, red blood cell production, bone density, mood, and sex drive. Because it touches so many systems, even a modest drop can show up in several parts of your life at once.

The relationship between how you feel and your lab number is not one-to-one. Some men with “normal” total testosterone (the total amount of testosterone in your blood, both bound to proteins and unbound) feel terrible, while others with borderline levels feel fine. That is why experts talk about biochemical hypogonadism, which means consistently low testosterone on blood tests plus compatible symptoms.^[1],[2]

Large population studies show that men with lower testosterone levels are more likely to have obesity, type 2 diabetes, metabolic syndrome, and higher cardiovascular and all-cause mortality, even after adjusting for age and lifestyle.^,[6] That does not prove low testosterone causes these problems, but it makes accurate testing a crucial part of understanding your overall health risk.

How it works

To really understand how to measure testosterone, you need to know which sample to use, which number matters, and how timing, lab methods, and your lifestyle can distort results.

Blood, not saliva or urine

Guidelines agree that serum testosterone — testosterone measured in a blood sample taken from a vein — is the standard for diagnosis in men.^[1],[2] Saliva tests and urine tests are unreliable because they are strongly affected by lab processing, time of day, and the fact that urine mainly reflects testosterone breakdown products rather than the active hormone itself.

Home testosterone tests that rely on saliva or urine can be useful for curiosity, but they should not be used to diagnose low testosterone or decide on TRT. If you want a number you and your doctor can act on, you need a venous blood draw.

Total testosterone: the starting point

Total testosterone is the first and most important lab when you are figuring out how to measure testosterone correctly. Total testosterone includes testosterone that is bound to proteins like sex hormone binding globulin (SHBG, a carrier protein that transports sex hormones in the blood) and albumin, plus a small unbound “free” fraction.^[1],[3]

Professional societies recommend drawing total testosterone between 7:00 and 10:00 am, on at least two separate mornings, because levels are highest then and can fluctuate day to day.^[1],[4] Many labs use immunoassays, a type of antibody-based test, which are acceptable for routine use but less precise near the low end of the range than liquid chromatography–mass spectrometry (LC–MS/MS), a more accurate method often used in reference laboratories.^[3]

Meta-analyses indicate that symptomatic men with total testosterone below 350 ng/dL (about 12 nmol/L) are most likely to benefit from TRT, while men above that threshold rarely see clear gains in sexual function or energy from testosterone alone.^[2],[5] In practice, many clinicians use 350 ng/dL as the “decision point,” especially if symptoms are significant.

Free testosterone and SHBG

Free testosterone is the tiny fraction of testosterone in your blood that is not bound to proteins and is able to enter cells and do the real work. Because SHBG levels change with age, weight, thyroid function, and some medications, two men with the same total testosterone can have very different free testosterone levels.^[2],[6]

Guidelines suggest checking free testosterone when total testosterone is borderline (roughly 300–400 ng/dL) or when SHBG is likely to be abnormal, such as in obesity, chronic liver disease, severe illness, or high thyroid hormone levels.^[2] Free testosterone can be measured directly with equilibrium dialysis, considered the gold standard, or estimated using a calculator that combines total testosterone, SHBG, and albumin; both are more reliable than simple “direct” free testosterone immunoassays in most men.^[3]

When men have persistent symptoms and total testosterone in the gray zone, a free testosterone below about 100 pg/mL (about 10 ng/dL) supports a diagnosis of hypogonadism and strengthens the case for TRT.^[2],[5]

Timing, fasting, and medications

Testosterone follows a diurnal rhythm, which means it peaks in the early morning and falls through the day; this rhythm is strongest in younger men and flattens somewhat with age.^[4] Acute illness, poor sleep, heavy alcohol use, severe calorie restriction, and intense endurance exercise in the previous 24 hours can all temporarily lower testosterone and make a single reading look worse than your true baseline.^[2],[4]

Opioid pain medications, glucocorticoids like prednisone, and prior anabolic steroid use can also suppress testosterone production at the testicular or pituitary level. When you plan how to measure testosterone, it is vital to tell your clinician about all prescriptions, over-the-counter drugs, and supplements you are using.

Most experts suggest drawing testosterone in the morning, after a normal night’s sleep, ideally fasting or at least before a large meal, and not during a major illness. If the first test is low, they recommend repeating it under similar conditions before you make decisions.^[1],[2]

Conditions linked to it

Knowing how to measure testosterone correctly matters most when you are dealing with conditions closely tied to low levels. The number on your lab report can help explain symptoms, uncover hidden disease, or flag risks that need attention.

• Metabolic syndrome and type 2 diabetes: Men with these conditions are more likely to have low total and free testosterone, and low testosterone itself predicts a higher risk of developing diabetes in the future.^,[6]
• Obesity: Extra body fat, especially around the abdomen, lowers testosterone by increasing conversion of testosterone to estradiol and by raising inflammatory signals that blunt testicular production.
• Cardiovascular disease: Observational studies link lower testosterone with higher rates of heart attacks, strokes, and overall mortality, though whether low testosterone is a cause, a marker of poor health, or both is still debated.
• Osteoporosis and fractures: In men, testosterone is a key driver of bone density. Unexplained fractures or a diagnosis of osteoporosis should trigger accurate testosterone testing.^[2]
• Infertility and low sperm counts: Disruption anywhere along the hypothalamic–pituitary–testicular axis (the hormone circuit that controls testosterone and sperm production) can show up as low testosterone plus low sperm numbers.
• Chronic opioid use and systemic steroids: Both classes of drugs can suppress the signals from the brain that tell the testicles to make testosterone, which is why measuring levels is standard in long-term users.

Limitations note: Many of these links come from observational or cohort studies, which are good at detecting associations but less reliable for proving cause and effect. Randomized trials of TRT show clear benefits for sexual function and modest gains in mood and bone density, but long-term effects on cardiovascular outcomes remain under active study.^[5]

Symptoms and signals

Even the best lab test only makes sense in the context of how you feel and function. Here are the main symptoms and signals that should push a man to learn how to measure testosterone properly and talk with a clinician:

• Lower sex drive than usual, with less interest in initiating sex
• Weaker or fewer morning erections
• Difficulty getting or keeping an erection, especially if it is new
• Noticeable loss of strength or muscle size despite training
• More body fat around the waist, even with similar eating and activity
• Fatigue that does not improve with rest
• Low mood, irritability, or feeling emotionally “flat”
• Problems with focus, memory, or motivation at work
• Reduced shaving frequency or slower beard growth
• Decreased exercise tolerance or slower recovery between workouts

Red-flag signs that need urgent medical evaluation — not just a testosterone test — include sudden testicular pain or swelling, breast tissue enlargement with nipple discharge, severe headaches with vision changes, or unexplained weight loss. These can signal serious conditions in the testicles or pituitary gland.

What to do about it

If you recognize the symptoms and want to know how to measure testosterone correctly, use a simple three-step plan: get proper labs, address contributors, and monitor over time.

1. Get a proper baseline blood test. Schedule a morning venous blood draw for total testosterone between 7:00 and 10:00 am, after a normal night’s sleep and without heavy drinking or intense late-night training. Ask that the sample be processed in a certified lab that uses calibrated methods. If the result is low or borderline, repeat the test on a different morning under similar conditions.^[1],[4]
2. Refine the picture with targeted testing and lifestyle changes. If total testosterone is consistently below about 350 ng/dL and you have clear symptoms, talk with a clinician experienced in men’s health about measuring free testosterone, SHBG, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin. At the same time, work on nutrition, sleep, alcohol, and training volume, since weight loss and better sleep alone can raise testosterone in many men.^[2],[6]
3. Decide on treatment and monitor regularly. If you meet both lab and symptom criteria for hypogonadism, TRT may be an option. When therapy starts, testosterone, blood counts, and prostate markers are usually checked every 3–6 months at first, then yearly, to ensure levels stay in a mid-normal range and side effects are caught early.^[1],[2]

Myth vs Fact

• Myth: Any “low” value on a home saliva test means you have low testosterone.
  Fact: Only repeat morning blood tests for total and, when needed, free testosterone can diagnose hypogonadism in men.
• Myth: If one testosterone test comes back low, you should start TRT right away.
  Fact: Guidelines require at least two low morning measurements plus compatible symptoms before starting therapy.
• Myth: Higher testosterone is always better.
  Fact: Pushing testosterone far above the normal range increases risks like thickened blood and sleep apnea, without proven long-term benefits.^[2]
• Myth: You can “hack” testosterone labs by timing the test after a huge workout or special supplement stack.
  Fact: Overtraining, lack of sleep, and random supplements are more likely to distort your number than improve it; your goal is an honest baseline, not a fake high score.
• Myth: A normal total testosterone level rules out hormone problems.
  Fact: In some men with abnormal SHBG or strong symptoms, free testosterone and other hormones still need to be measured.

Bottom line

Knowing how to measure testosterone the right way means using morning blood tests, repeating them, and interpreting both total and, when needed, free testosterone in the context of your symptoms and overall health. Saliva and urine kits can spark curiosity, but they should not drive decisions. When you pair accurate lab work with honest conversations about how you feel, you give yourself the best chance of choosing the right mix of training, nutrition, stress management, and, if needed, medical therapy to get back to feeling like yourself.

References

1. Mulhall JP, Trost LW, Brannigan RE, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline. The Journal of urology. 2018;200:423-432. PMID: 29601923
2. Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. The Journal of clinical endocrinology and metabolism. 2018;103:1715-1744. PMID: 29562364
3. Taieb J, Mathian B, Millot F, et al. Testosterone measured by 10 immunoassays and by isotope-dilution gas chromatography-mass spectrometry in sera from 116 men, women, and children. Clinical chemistry. 2003;49:1381-95. PMID: 12881456
4. Brambilla DJ, Matsumoto AM, Araujo AB, et al. The effect of diurnal variation on clinical measurement of serum testosterone and other sex hormone levels in men. The Journal of clinical endocrinology and metabolism. 2009;94:907-13. PMID: 19088162
5. Corona G, Isidori AM, Buvat J, et al. Testosterone supplementation and sexual function: a meta-analysis study. The journal of sexual medicine. 2014;11:1577-92. PMID: 24697970
6. Selvin E, Feinleib M, Zhang L, et al. Androgens and diabetes in men: results from the Third National Health and Nutrition Examination Survey (NHANES III). Diabetes care. 2007;30:234-8. PMID: 17259487
7. Corona G, Goulis DG, Huhtaniemi I, et al. European Academy of Andrology (EAA) guidelines on investigation, treatment and monitoring of functional hypogonadism in males: Endorsing organization: European Society of Endocrinology. Andrology. 2020;8:970-987. PMID: 32026626