⚠️ Educational only. LabPlain does not provide medical advice or diagnosis. Always discuss your specific results with your healthcare provider.
What this test measures
Testosterone is the primary sex hormone in males, though it plays important roles in females too. In men, it's produced mainly by the testicles and is responsible for developing male reproductive tissue, maintaining muscle mass and bone density, regulating sex drive, and producing red blood cells. In women, it's made in smaller amounts by the ovaries and adrenal glands.
A testosterone blood test measures the total amount of testosterone circulating in your blood. Most testosterone is bound to proteins (primarily sex hormone-binding globulin, or SHBG) and is inactive — only a small fraction is "free" testosterone that your body can actually use. Some panels measure both total and free testosterone.
Doctors order this test to evaluate low sex drive, erectile dysfunction, infertility, delayed or early puberty, unexplained fatigue, or symptoms that suggest a hormonal imbalance. It's also used to monitor testosterone replacement therapy.
Normal reference range
Men: 300–1,000 ng/dL | Women: 15–70 ng/dL
These are general reference ranges — your lab's printed range takes priority. Values vary by age: men's testosterone peaks in their 20s and gradually declines about 1–2% per year after 30. Women's levels also decline with age and drop significantly after menopause.
Results may be reported in ng/dL or nmol/L depending on the lab. To convert: 1 ng/dL ≈ 0.035 nmol/L.
⏰ Why morning draws matter
Testosterone levels follow a daily rhythm, peaking between 7–10 AM and dropping by 20–30% by afternoon. For accurate results, most doctors request a morning blood draw — ideally before 10 AM. An afternoon result that appears borderline low may actually be normal.
What your result might indicate
↑ If High
Elevated testosterone in men may indicate anabolic steroid use, certain tumors of the testicles or adrenal glands, or congenital adrenal hyperplasia. In women, high testosterone can signal polycystic ovary syndrome (PCOS), adrenal disorders, or ovarian tumors.
↓ If Low
Low testosterone (hypogonadism) in men may result from aging, obesity, type 2 diabetes, pituitary disorders, testicular damage, or certain medications. In women, low testosterone can cause fatigue, low libido, and reduced bone density, though it's less commonly diagnosed.
Symptoms associated with abnormal testosterone
↑ High Testosterone Symptoms
Acne or oily skin
Aggressive behavior or mood swings
Increased body or facial hair (women)
Irregular or absent periods (women)
Enlarged clitoris (women)
Testicular shrinkage (men on exogenous T)
Sleep apnea
Elevated red blood cell count
↓ Low Testosterone Symptoms
Low sex drive (libido)
Erectile dysfunction (men)
Fatigue and low energy
Loss of muscle mass
Increased body fat, especially abdominal
Depressed mood or irritability
Reduced bone density
Difficulty concentrating or brain fog
Common causes of abnormal testosterone
What can raise testosterone?
The most common cause of elevated testosterone in otherwise healthy adults is exogenous testosterone — meaning testosterone taken as medication or anabolic steroids. Outside of that, testosterone-secreting tumors of the adrenal glands or gonads are a rare but serious cause. In women, polycystic ovary syndrome (PCOS) is the most frequent reason for elevated testosterone, affecting roughly 1 in 10 women of reproductive age.
Congenital adrenal hyperplasia (CAH), a genetic condition affecting how the adrenal glands produce hormones, can also cause elevated androgens including testosterone in both sexes.
What can lower testosterone?
In men, the most common cause is age-related decline — testosterone drops gradually after age 30, and by age 70 many men have levels well below the peak range. Obesity is strongly associated with low testosterone because fat tissue converts testosterone into estrogen. Other contributors include type 2 diabetes, sleep apnea (especially untreated), chronic stress, opioid medications, and conditions affecting the pituitary gland or testicles directly.
In women, low testosterone most often reflects natural aging and menopause, or surgical removal of the ovaries.
Tests often ordered alongside testosterone
Testosterone rarely tells the whole story on its own. Your doctor may also order:
Free testosterone — measures the biologically active fraction not bound to proteins; more useful than total testosterone in some cases
LH (Luteinizing Hormone) — helps determine if low testosterone originates in the testicles or in the pituitary gland
FSH (Follicle-Stimulating Hormone) — evaluated alongside LH to assess the hypothalamic-pituitary-gonadal axis
SHBG (Sex Hormone-Binding Globulin) — high SHBG can make total testosterone look normal while free testosterone is actually low
Estradiol — important in men with low testosterone, since excess estrogen can suppress testosterone production
Complete blood count (CBC) — testosterone affects red blood cell production; polycythemia is a risk with TRT
PSA (Prostate-Specific Antigen) — monitored in men on testosterone replacement therapy
What to do next
A single testosterone result — especially one that's borderline — rarely leads to a diagnosis on its own. Your doctor will look at your symptoms, repeat the test on a different day (ideally morning), and often order additional hormone panels before recommending treatment. If you're experiencing significant symptoms of low or high testosterone, ask specifically about free testosterone and SHBG, not just the total number.
Questions to ask your doctor
01Is my result total testosterone or free testosterone — and does my free level look normal?
02Was this drawn in the morning? Should we repeat it to confirm?
03Could my SHBG level be affecting how we interpret this result?
04What's causing my testosterone to be low or high — is it coming from the testicles/ovaries or the pituitary?
05Do my symptoms actually match what you'd expect from this result?
06If testosterone replacement therapy is an option, what are the risks and monitoring requirements?
Frequently asked questions
What's the difference between total and free testosterone?
Total testosterone measures all testosterone in your blood — both the portion bound to proteins (inactive) and the free fraction (active). Free testosterone is the only form your cells can actually use. Some men have normal total testosterone but low free testosterone due to high SHBG levels, meaning their bodies have less usable hormone than the total number suggests.
Is 300 ng/dL really "low" for a man?
Technically, 300 ng/dL sits at the bottom of most reference ranges — it's not flagged as abnormal on a lab report. But whether it causes symptoms depends on the individual. Some men feel fine at 300; others feel significant fatigue, low libido, and mood issues. The number alone doesn't determine treatment — symptoms matter just as much.
Can women have testosterone problems too?
Yes. In women, high testosterone is most commonly linked to PCOS — a hormonal condition affecting the ovaries — and can cause irregular periods, excess hair growth, and acne. Low testosterone in women can contribute to fatigue and low libido, though it's less commonly evaluated and treated than in men.
Does testosterone replacement therapy have risks?
Yes. TRT can raise red blood cell counts (increasing clot risk), suppress natural sperm production (affecting fertility), cause acne and hair loss, and requires PSA monitoring in men over 40. It's generally appropriate when levels are genuinely low and symptoms are present — not simply for optimization in men with normal levels.
Can lifestyle changes raise low testosterone?
For men with low testosterone driven by lifestyle factors — obesity, poor sleep, sedentary habits, chronic stress — meaningful improvements are possible without medication. Weight loss, resistance training, quality sleep (7–9 hours), and stress reduction have all been shown to raise testosterone levels. These won't fix structural problems like testicular damage or pituitary disorders, but they're worth addressing first.