Low testosterone can either be diagnosed clinically, that is by symptoms consistent with low testosterone, or by absolute laboratory values.
The inherent problem with the absolute laboratory value diagnosis of low testosterone, is that we don’t know consistently at which level a man will have symptoms of low testosterone. And we don’t know at what level on a laboratory test and men may benefit from testosterone replacement.
The recent International Expert Consensus Resolutions on Testosterone Deficiency published in the Mayo Clinic proceedings in 2016 identified that there was no specific blood level that predicted which men benefit from testosterone replacement therapy in which would not.
Yet many physicians, health insurance companies, and even the FDA use absolute laboratory values to identify a diagnosis of low testosterone.
We now know that men with lower testosterone levels, and symptoms of low testosterone generally benefit from testosterone replacement. We know that men with low testosterone who are not treated with testosterone replacement have higher incidences of obesity, diabetes, heart attacks, and strokes.
Testosterone replacement in men with symptoms of of low testosterone leads to better overall health, better well-being, better quality of life, and better sexuality. It also leads to weight loss in overweight men.
So how common is low testosterone?
There are certainly age-related changes in testosterone level. It’s estimated that testosterone level will drop 1 to 2% per year. Some men slower, and some men faster.
There are various ways to measure symptoms of low testosterone. One is called the ADAM (Androgen Deficiency in the Aging Male) questionnaire, and the other one is called the AMS (Aging Male Symptoms) scale.
Both the ADAM and AMS scales are very sensitive for detecting low testosterone and identifying which men may benefit from testosterone replacement. Sensitive means that if you have the condition of low testosterone, the score will likely tell you that.
There is a debate as to the specificity of the ADAM and AMS scales. Specificity refers to accuracy. In this is where the absolute blood test level comes in the play.
If we set a threshold to diagnose low testosterone with a severely low blood level of 280 ng/Dl, than the specificity is around 20 to 30%. If we use a more realistic low testosterone blood level of lower than 450 ng/dL, then the ADMA and AMS scales are highly accurate.
