What to Know about the Testosterone Test

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.
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.

What is a testosterone test?

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.

These include:

  • stress
  • 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

Testosterone levels also vary with age and major growth events, such as puberty.

How do they work?

A testosterone test is a simple form of a 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.

Why test for testosterone?

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)
  • infertility
  • 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

Symptoms of low testosterone

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.

Those with low T who have testosterone therapy may find improvement in their symptoms. A review 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.

Symptoms of high testosterone

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
  • baldness
  • skipped periods or no periods

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.