Testosterone tests measure levels of testosterone in the blood. Testosterone is an essential hormone in males and females but is the main sex hormone in males. It helps with muscle development, voice deepening, and sperm production.
Females have much lower amounts of testosterone than males. In females, it helps balance hormones, regulates some bodily functions, and contributes to libido.
There are two types of testosterone in the blood. Bound testosterone binds to different proteins, such as albumin and sex hormone-binding globulin (SHBG) in the blood, and free testosterone does not attach to proteins.
A testosterone test may help doctors gauge if a person has too much or too little testosterone in their blood, which could help them diagnose underlying conditions.
There are two types of testosterone tests: one that measures total (bound and free) testosterone in the blood and one that measures free testosterone.
A person may have reduced testosterone levels for a variety of reasons. A doctor may order the different tests based on what they suspect the issue is.
Recent guidelines indicate that the normal T range for morning testosterone levels in males is 300–1,000 nanograms per deciliter (ng/dL). However, it is important to note that normal T depends on a variety of factors and influences.
- comorbid medical conditions
- time of the draw (AM vs. PM)
- age: what is normal for a 20-year-old would not be normal for a 90-year-old
Women’s testosterone levels tend to be lower. A small sample from the Centers for Disease Control and Prevention (CDC) noted a range from about 8-49ng/dL.
However, these are average ranges. It is normal for testosterone levels to fluctuate a bit on an individual level.
Testosterone levels also vary with age and major growth events, such as puberty.
A testosterone test is a simple form of blood test. Doctors will first conduct a physical examination, looking for signs of low or high testosterone levels. They may ask about medical history and any medications the person takes before ordering the blood test.
Doctors tend to carry out tests in the morning when testosterone levels are highest. The blood test involves taking a sample of blood from the arm using a small needle. This process typically takes a few minutes.
Some people may have to follow some special instructions before the test. A doctor may ask the person to stop taking prescription drugs that could affect hormone levels, such as androgen or estrogen therapies.
Other prescription or recreational drugs and herbs and supplements may also affect testosterone levels, so people should always let their doctor know about anything they are taking.
Doctors may order more than one test, taken on different days. This may help get a more accurate average of testosterone levels.
Depending on the results, doctors may order further tests to confirm their diagnosis.
There are several at-home testing kits to measure testosterone levels. These kits involve taking a saliva swab to check for hormone levels.
The person sends their saliva sample to the lab associated with their at-home kit.
Experts continue to debate the accuracy and reliability of home salivary testosterone tests. While these kits offer a quick and easy way to check for testosterone levels, the gold standard for accuracy remains a blood test.
As a study in Human Kinetics Journals notes, saliva tests do not track changes in the hormone levels as quickly or accurately as serum tests.
No test will replace a doctor’s diagnosis, and at-home kits are unable to diagnose any condition that may be causing low T. Anyone who gets any abnormal values from a home test or normal values when they have clinical symptoms should see their doctor for a diagnosis.
A testosterone test is an important tool for doctors to help them understand a person’s hormonal balance and the risk for some conditions.
Doctors may order the test to help diagnose a number of conditions such as:
- erectile dysfunction (ED)
- decreased sex drive
- delayed puberty
- early puberty
- irregular menstrual periods
- excess body hair growth
- tumors in the testicles
- issues in the hypothalamus
- conditions of the pituitary gland
- abnormal weight gain
- low energy levels
- loss of muscle mass
- hot flashes
In males, doctors may order a testosterone test if they suspect a person has low T levels.
Symptoms of low T include:
- overall fatigue
- low sex drive
- difficulty getting or maintaining an erection
- early hair loss
- loss of muscle mass
- weak bones
- fertility issues
- development of breast tissue
In cases of low T, doctors may prescribe testosterone products, such as patches, topical gels, and injections, to increase testosterone levels.
TheFood and Drug Administration (FDA) have only approved these products for use in males with associated medical conditions causing low T.
Those with low T who have testosterone therapy may find improvement in their symptoms. A review in BMJ Open found that testosterone replacement therapy helped improve quality of life, ED, and libido in men with low T.
Anyone who thinks they have symptoms of low T should contact their doctor for a full diagnosis.
People with high testosterone (high T) levels may experience the following symptoms:
- growing facial hair
- growing more or thicker body hair
- deepening of the voice
- loss of breast tissue
- acne and oily skin
- skipped periods or no periods
High testosterone in females may indicate conditions in the ovaries, such as ovarian cancer or polycystic ovary syndrome (PCOS).
Anyone who feels they have high T levels should contact their doctor for a diagnosis.
Testosterone levels that are too high or too low can both cause issues in the body. Testosterone tests help identify levels of total or free testosterone in the body. These levels may be key in helping to diagnose any underlying issues.
Testosterone tests only give a glimpse of the testosterone levels at one moment in time. Doctors may order more than one test to see how the levels vary based on other factors. A single test is not enough to diagnose any underlying condition.
Anyone who suspects their testosterone levels are too high or too low should work closely with their doctor to diagnose the issue.