Testosterone is a hormone that plays a role in sex drive, muscle, hair growth, and more. It is often thought of as a male hormone, but women make it too, just in smaller amounts. If you have been feeling off and wonder whether your hormones are involved, a testosterone blood test is one tool a clinician may use to learn more.
Here is a plain-language look at what the test measures, why the time of day matters, what can affect your levels, and how to talk with a clinician about your symptoms.
What the test measures
Testosterone travels through your blood in two forms. According to MedlinePlus, all the testosterone in your blood is either bound to proteins or unbound, which is called free. Most of it attaches to two proteins: sex-hormone-binding globulin (SHBG) and albumin.
MedlinePlus describes two main types of tests:
- Total testosterone measures both bound and free testosterone. This is the most common test.
- Free testosterone measures only the unattached form.
Your clinician decides which test makes sense based on your symptoms and health history.
Why morning timing matters
Testosterone levels are typically highest in the morning. That is why MedlinePlus notes that blood is usually drawn between 7 and 10 a.m.
Timing matters because a sample taken at another time of day may not reflect your usual morning level. The MedlinePlus Medical Encyclopedia also notes that a repeat sample may be needed if a first result seems unexpectedly low.
The Endocrine Society explains that diagnosing low testosterone in men involves at least two early morning blood tests showing low levels, along with symptoms. A clinician will also do a physical exam and review your medical history. In other words, one number alone is not the whole story.
How to prepare
- You may need to fast (not eat or drink) for several hours before the test. Ask your provider what to do.
- Tell your provider about every medicine and supplement you take. Some can affect results, and your provider may give you instructions before the test. Do not stop any medicine on your own.
- Plan for a morning blood draw if your provider recommends it.
Understanding the numbers
Testosterone is often reported in nanograms per deciliter (ng/dL). As one example, the MedlinePlus Medical Encyclopedia lists these normal ranges:
- Males ages 17 to 50: 249 to 836 ng/dL
- Males over 50: 193 to 740 ng/dL
- Females ages 17 to 50: 8.4 to 48.1 ng/dL
- Females over 50: 2.9 to 40.1 ng/dL
Normal ranges may vary slightly among labs, so the range on your own report is the one to use. MedlinePlus adds that results depend on your age, sex, and other health conditions.
MedlinePlus is also clear that a testosterone test alone can't diagnose a health condition. Abnormal results along with symptoms may be a sign of a health problem. That is why a clinician looks at the full picture.
What can affect testosterone levels
Age
According to the Endocrine Society, testosterone levels naturally decrease by about 1% each year after age 30. This gradual change does not usually lead to very low levels on its own, even in older age.
Health conditions
The Endocrine Society notes that low testosterone is more common in older men, men with obesity, and men with type 2 diabetes. The MedlinePlus Medical Encyclopedia lists other possible causes of lower levels, including:
- Chronic illness
- Low thyroid function
- Diseases of the testes
- Obesity
- Sleep problems such as obstructive sleep apnea
Medicines and other factors
The Endocrine Society lists certain medicines, such as opioids and corticosteroids, as possible causes of low testosterone. Other causes it lists include injury to the testes, cancer treatments, hormone disorders, chronic diseases like diabetes and liver disease, genetic conditions, and anabolic steroid use.
Levels can also be higher than expected. The MedlinePlus Medical Encyclopedia notes that high testosterone may be related to tumors of the ovaries, cancer of the testes, or taking medicines or drugs that raise testosterone.
Symptoms people discuss with clinicians
People often ask about testing because of changes they have noticed. These symptoms can have many causes. They are a reason for a conversation, not a diagnosis.
Symptoms linked with low testosterone in men
- Low sex drive
- Trouble getting or keeping an erection
- Lower energy
- Loss of muscle mass
- Mood changes, such as irritability or depression
- Infertility
- Enlarged breasts or less face and body hair
Symptoms linked with high testosterone in women
- Unusual hair growth on the face or body
- Hair loss on the head that may look like male-pattern baldness
- Voice changes
- Irregular or missed periods
- Acne
MedlinePlus also notes that in children and teens, a testosterone test may help find the cause of early or delayed puberty.
Questions to ask your clinician
- Should I have total testosterone, free testosterone, or both checked?
- What time should my blood be drawn, and do I need to fast?
- Could any of my medicines or supplements affect the result?
- Should the test be repeated before we draw conclusions?
- What else could explain my symptoms, such as sleep, thyroid, or other health issues?
The bottom line
A testosterone test measures the hormone in your blood, usually as total or free testosterone. Morning timing, repeat testing, medicines, and health conditions all shape what the number means. Your symptoms and results, reviewed together by a licensed clinician, give a much clearer picture than any single test.
At Talvi, a licensed clinician reviews your health history before anything is prescribed. At-home testing is coming to Talvi, with results explained by a licensed provider.
If you have symptoms that feel severe or urgent, seek emergency care or call 911.