How to Test Testosterone Levels: Timing and Results

A testosterone test measures the hormone in a blood sample, but getting a useful answer requires more than ordering one number.⁵ Testosterone changes during the day and can be affected by sleep, food intake, illness, medications, body composition, and the laboratory method.

For suspected low testosterone in men, current guidance calls for compatible symptoms plus at least two low morning measurements. A single low result does not diagnose hypogonadism.

Who may need testosterone testing?

In adult men, testing is most useful when symptoms or signs suggest testosterone deficiency. These may include:

• Low sexual desire
• Fewer spontaneous or morning erections
• Erectile dysfunction
• Infertility or a low sperm count
• Loss of muscle mass or body hair
• Small testes or breast enlargement
• Unexplained anemia or low bone density

Fatigue, depressed mood, poor concentration, and reduced exercise performance are less specific. They may still justify a broader medical evaluation, but they do not point to testosterone alone.

In women, testosterone testing is more commonly used to evaluate signs of androgen excess, such as new coarse facial hair, acne, scalp hair loss, irregular periods, or virilization. It may also be used to monitor carefully prescribed testosterone therapy.

The Endocrine Society recommends against routine screening for hypogonadism in the general male population.¹

What time should testosterone be tested?

For men, total testosterone should usually be measured in the morning, when levels tend to be highest. The Endocrine Society recommends repeating a low result with another morning fasting measurement.¹

Shift workers and men with irregular sleep schedules may need individualized timing based on their main sleep period rather than a rigid clock time. Tell the ordering clinician about night work, severe sleep loss, recent illness, or unusual exercise.

Do not test during an acute illness if the goal is to establish a stable baseline. Severe illness, poor nutrition, and some medications can temporarily suppress testosterone.

Total testosterone, free testosterone, and SHBG

Total testosterone

Total testosterone measures the hormone that is bound to proteins plus the small unbound fraction. It is the standard first test because it is widely available and has the best-developed reference ranges.

Free testosterone

Free testosterone is the unbound portion. It may be helpful when total testosterone is close to the lower limit or when SHBG is likely to be abnormal. Accurate direct measurement generally requires equilibrium dialysis. A calculated estimate can also be used when total testosterone, SHBG, and albumin are measured reliably.²

Some direct free-testosterone immunoassays are less reliable. The method printed on the report matters.

Sex hormone binding globulin

SHBG carries testosterone in the blood. Low SHBG can make total testosterone look low even when free testosterone is less affected. High SHBG can make total testosterone look reassuring while free testosterone is lower.

Obesity, insulin resistance, thyroid disease, liver disease, aging, oral contraceptives, and some medicines can alter SHBG.

Why a low result should be repeated

Testosterone has biological and analytical variability. A repeat test helps prevent a temporary dip or measurement problem from becoming a lifelong diagnosis.

A 2022 review recommended two or more fasting morning samples and emphasized accurate total testosterone measurement with a standardized method.²

If the second result is normal, the clinician may review sleep, illness, medications, timing, and the degree of symptoms before deciding whether any further testing is useful.

Tests that help identify the cause

Once low testosterone is confirmed, the next question is why.

• Luteinizing hormone, or LH: Stimulates testosterone production in the testes.
• Follicle stimulating hormone, or FSH: Supports sperm production and helps assess testicular function.
• Prolactin: May be elevated with certain pituitary conditions or medications.
• Iron studies: May be used when iron overload is a concern.
• Thyroid testing: May help when symptoms or SHBG changes suggest thyroid disease.
• Semen analysis: Assesses fertility and is not replaced by a testosterone result.

High LH and FSH with low testosterone can suggest a primary testicular problem. Low or inappropriately normal LH and FSH can point toward a pituitary, hypothalamic, medication-related, or functional cause. The Endocrine Society recommends LH and FSH to distinguish primary from secondary hypogonadism.¹

Imaging is not automatic. Pituitary imaging is reserved for patterns, symptoms, or laboratory findings that create a clinical reason to look for a structural problem.

How to interpret the result

Use the reference range from the performing laboratory. Assay methods and reference populations differ, so copying a range from another website can be misleading.

A harmonized study in healthy, nonobese men ages 19 to 39 reported a total testosterone range of 264 to 916 ng/dL when measurements were calibrated to a reference method.³ This range provides context, but it is not a universal treatment threshold.

Read our detailed guide to testosterone ranges by age and sex before comparing numbers across laboratories.

What can distort a testosterone test?

• Testing later in the day
• Acute illness or recent hospitalization
• Severe sleep loss or an irregular sleep schedule
• Under-eating, rapid weight loss, or excessive training
• Obesity and altered SHBG
• Opioids, glucocorticoids, anabolic steroids, and other medicines
• Laboratory method and calibration

Tell the clinician about all prescription drugs, over-the-counter products, hormones, and supplements. Do not stop a medication just to change the result unless instructed.

At-home testosterone tests

At-home kits can offer convenience, but collection method, timing, sample handling, assay quality, and follow-up vary. Saliva and finger-prick results should not automatically be treated as equivalent to a properly collected serum test.

If an at-home result is abnormal or symptoms are significant, confirm it through a qualified clinician and a reliable laboratory before making treatment decisions.

Testing before testosterone therapy

Before treatment, a clinician should confirm the diagnosis, investigate the cause, review contraindications, and discuss fertility. Monitoring may include testosterone concentration, blood count or hematocrit, symptom response, side effects, and prostate-related assessment based on age and risk.

Testosterone can suppress sperm production. Men interested in current or future fertility should not receive exogenous testosterone without specialist discussion.⁴ This is especially important for men under 30. See our article on low testosterone in younger men.

Frequently asked questions

Do I need to fast for a testosterone test?

The Endocrine Society recommends confirming a low result with a morning fasting measurement. Follow the ordering clinician's instructions because other tests drawn at the same time may also require fasting.

Is one low testosterone test enough?

No. Diagnosis generally requires compatible symptoms and repeat low morning measurements.

Should women test testosterone in the morning?

Timing depends on the clinical question, menstrual status, and laboratory. When evaluating androgen excess, specialty guidance may call for early morning testing. Follow the ordering clinician's directions.

Can I diagnose low testosterone from symptoms alone?

No. Many symptoms overlap with sleep disorders, depression, thyroid disease, medication effects, obesity, diabetes, and other conditions. Laboratory confirmation is required.

Bottom line

Useful testosterone testing starts with a clear clinical question. Men with symptoms of deficiency generally need morning total testosterone measured at least twice, followed by free testosterone or cause-focused tests when indicated. Laboratory method, SHBG, health status, medications, and fertility goals all affect interpretation.

Sources

1. Endocrine Society. Testosterone Therapy for Hypogonadism Guideline Resources.
2. Jasuja R, et al. Accurate Measurement and Harmonized Reference Ranges for Total and Free Testosterone Levels. Endocrinology and Metabolism Clinics of North America. 2022.
3. Travison TG, et al. Harmonized Reference Ranges for Circulating Testosterone Levels in Men of Four Cohort Studies in the United States and Europe. Journal of Clinical Endocrinology and Metabolism. 2017.
4. American Urological Association and American Society for Reproductive Medicine. Diagnosis and Treatment of Infertility in Men. Amended 2024.
5. MedlinePlus. Testosterone Levels Test.

Evidence reviewed August 2026. This article is educational and is not a substitute for individualized medical diagnosis or treatment.