Question

Endocrine System

How are testosterone levels measured?

A Answers (2)

  • AMichael Roizen, MD, Internal Medicine, answered
    While the majority of erectile-dysfunction cases are caused by vascular issues, about 20 percent are associated with low testosterone levels. As part of a checkup to determine the root of erectile difficulties, your doctor could measure your hormone levels. Though it's a simple blood test, it's unlike most others, because testosterone is not measured directly.

    To get an accurate assessment of your testosterone levels, you need to have two measurements. One measures the combined level of bound testosterone and free testosterone (the active kind that matters in terms of what symptoms you're experiencing) in your blood, while the other measures only the testosterone that's bound to proteins. By subtracting the second number from the first, you'll find your level of free testosterone. Because free testosterone can bind protein in a test tube, and bound testosterone can be displaced, the resulting number will be, at best, a close approximation.
  • AMike Carragher, DO, Age Management Medicine, answered
    Testosterone levels can be accurately measured by a simple blood test.  Be sure to ask your doctor to measure your FREE testosterone level. Free testosterone is the testosterone that is available for your body to use.  Testosterone is an important hormone for not only sex drive and lean muscle building, but for cardiac function, brain function, bone health, mood, and many other critical body functions. Many physicians only test total testosterone levels, which may not be an accurate reflection of biologically active testosterone.  Health outcomes and quality of life are better for people who have free testosterone levels in the upper 1/3 of the normal range.  
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