For adult men, a total testosterone level below 300 ng/dL, or about 10.4 nmol/L, is commonly considered low. A single low result does not confirm testosterone deficiency. Diagnosis generally requires:
- Symptoms or signs associated with low testosterone
- Two separate early-morning tests showing consistently low levels
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Low Testosterone at a Glance
| Measure | What it usually means |
|---|---|
| Total testosterone below 300 ng/dL | A common threshold for possible testosterone deficiency in adult men |
| One low test result | Not enough to confirm testosterone deficiency |
| Two low morning results plus symptoms | Supports a diagnosis of testosterone deficiency |
| Borderline total testosterone | A clinician may check free testosterone and SHBG |
| Low testosterone without symptoms | May not meet the clinical definition of hypogonadism |
Laboratory ranges vary, and testosterone levels change throughout the day. A clinician also considers your age, symptoms, health conditions, medications and the laboratory's testing method.
Why Are Two Testosterone Tests Needed?
Testosterone levels are usually highest in the morning. Illness, differences between laboratory tests and normal day-to-day variation can lower a result temporarily.
The American Urological Association recommends two total testosterone measurements taken on separate occasions, preferably in the early morning.
The Endocrine Society also recommends repeating a morning, fasting total testosterone test before diagnosing hypogonadism.
A typical testing approach is:
- Have the blood sample taken in the morning, often between 7 a.m. and 10 a.m.
- Repeat the test on a different day if the first result is low
- Tell the clinician about medications, illness, sleep problems and supplements
- Avoid relying on a result taken during a serious acute illness without medical advice
MedlinePlus notes that testing is usually done in the morning because testosterone levels are typically highest then.
What Symptoms Are Associated With Low Testosterone?
Symptoms that may support a diagnosis include:
- Reduced sex drive
- Fewer spontaneous or morning erections
- Erectile difficulties
- Infertility or a low sperm count
- Loss of muscle mass or strength
- Increased body fat
- Reduced body or facial hair
- Enlarged or tender breasts
- Low bone density
- Unexplained anemia
- Low mood, difficulty concentrating or reduced energy
Reduced libido and fewer spontaneous erections are among the more specific symptoms. Fatigue, low mood and poor concentration can also result from depression, sleep apnea, diabetes, medication effects or thyroid problems.
Is a Testosterone Level Below 300 ng/dL Always Low?
No. A level below 300 ng/dL is a screening threshold, not a diagnosis by itself.
The American Urological Association states that total testosterone below 300 ng/dL alone does not define testosterone deficiency. Compatible symptoms or signs are also required.
Some men have symptoms even when their total testosterone is near the lower end of the laboratory range. In that situation, a clinician may check free testosterone, especially when sex hormone-binding globulin, or SHBG, may be affecting the total result.
Free testosterone is the portion that is not attached to blood proteins and is more available for tissues to use.
Total Testosterone Versus Free Testosterone
A total testosterone test measures both protein-bound and unbound testosterone. It is usually the first test used.
A free testosterone test measures the unbound portion. It may provide more information when:
- Total testosterone is close to the lower limit
- Symptoms do not match the total testosterone result
- Obesity or another condition may have changed SHBG levels
- The clinician suspects an unusual protein-binding pattern
Free testosterone should be interpreted with the testing method and laboratory reference range in mind.
What Can Cause Low Testosterone?
Low testosterone can result from problems involving the testicles, pituitary gland or hypothalamus. Other possible contributors include:
- Obesity
- Chronic kidney or liver disease
- Diabetes and other long-term illnesses
- Certain medications, including some opioids and chemotherapy drugs
- Testicular injury or disease
- Pituitary disorders
- Genetic conditions
- Excessive alcohol use
- Severe illness or temporary infection
Obesity can lower SHBG, which may make testosterone results harder to interpret. In some men, total testosterone is low while free testosterone remains within the normal range.
What Happens After a Low Testosterone Result?
A clinician may repeat the test and order other tests to identify the cause. These may include:
- Free testosterone and SHBG
- Luteinizing hormone, or LH
- Follicle-stimulating hormone, or FSH
- Prolactin
- Thyroid tests
- Complete blood count
- Semen analysis when fertility is a concern
LH and FSH can help distinguish primary hypogonadism, which starts in the testicles, from secondary hypogonadism, which involves the pituitary gland or hypothalamus.
Testosterone replacement therapy is not appropriate for every low result. It can reduce sperm production and may not be suitable for men who are trying to conceive without specialist advice. The cause should be assessed before treatment begins.
What Is Considered Low Testosterone in Women?
Women normally have much lower testosterone levels than men, so the adult male threshold of 300 ng/dL does not apply to women.
Female testosterone results must be interpreted using the person's sex, age, menstrual status, symptoms and the laboratory's reference range. Very low levels may sometimes be linked to adrenal, pituitary or ovarian conditions, but no single cutoff applies to every woman.
Bottom Line
A testosterone level below 300 ng/dL may indicate low testosterone in an adult man, but the result needs to be confirmed with properly timed repeat testing and assessed alongside symptoms or signs. One low result is a reason for follow-up, not a reason to start testosterone treatment without medical evaluation.