Testing for Testosterone
Answers to common questions about testing for testosterone.
Questions on this page
When should testosterone be tested?
Testing is generally appropriate when a man has symptoms or signs suggestive of testosterone deficiency.
What is the best time to test testosterone?
Testosterone has a daily rhythm and is usually measured in the early morning, preferably when the person is well and not acutely ill.
Is one low testosterone report enough?
Usually not. A diagnosis should generally be confirmed with a repeat morning testosterone measurement, particularly when the initial result is low or borderline.
What is total testosterone?
Total testosterone measures the testosterone circulating in the blood, including testosterone bound to proteins and the free fraction.
What is free testosterone?
Free testosterone is the small fraction of testosterone that is not bound to proteins. It may be useful in selected men, particularly when total testosterone is borderline or when SHBG abnormalities are suspected.
What is SHBG?
Sex hormone-binding globulin (SHBG) is a protein that binds testosterone and affects how much testosterone is available to tissues.
What other tests may be needed?
Depending on the situation, an endocrinologist may consider:
- LH
- FSH
- Prolactin
- SHBG
- Free or calculated free testosterone
- Thyroid function tests
- Iron studies
- Semen analysis when fertility is a concern
- Other pituitary investigations when indicated