1. Low Testosterone Pictures Slideshow
2. Take the Low Testosterone (Low T) Quiz
3. Impotence Pictures Slideshow

Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Low-T is presumptively diagnosed by the person's history of signs and symptoms (see low-T symptoms previously) and by physical examination.

For males, a blood test is available that can detect testosterone levels and provides the basis for a definitive diagnosis for low-T. Normal values vary from 270 – 1070 ng/dl but the definition of "normal" varies slightly according to different experts. Most blood test measurements are done in the morning because that is when the daily production of testosterone in males is highest.

Blood tests for females and children are more variable in results (some researchers suggest females have about one-third to one-eighth the male level of testosterone, while male infants and children before puberty may have less than 30 ng/dl and girls less than 10 ng/dl) so the diagnosis is more difficult and often based on symptoms and physical findings.

In addition, other tests (blood, imaging) may be done to diagnose if the low-T has secondary or tertiary causes or if underlying diseases are contributing to symptom development or inhibiting testosterone production.

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