Serum PSA and Testosterone Levels

Serum PSA levels may useful for diagnosing hypogonadism (low testosterone), Italian researchers say.
In the past, the relationship between PSA levels and testosterone has been difficult to define, as some researchers have found a connection and others have not.

The goals of this study were to better understand this possible relationship for men with sexual dysfunction and to determine whether PSA levels may give information about testosterone levels.

Almost three thousand men participated in the study. All of them were seeking treatment for sexual dysfunction and had PSA levels of less than 4 ng/mL. They ranged in age from 18 to 85 with a mean age of 52.5 ± 12.4 years.


A variety of physical measurements were conducted, including blood pressure, waist circumference, testis volume, total testosterone, HDL cholesterol, and triglycerides. Also, each man was interviewed using the Structured Interview on Erectile Dysfunction (SIEDY), ANDROTEST, a tool that screens for hypogonadism in men with erectile dysfunction, and PsychoANDROTEST, which examines the psychological signs and symptoms of low testosterone.

After adjusting for age, the researchers found that low PSA levels were associated with delayed puberty and lower testis volume, two markers of hypogonadism. Low PSA was also associated with metabolic syndrome, type 2 diabetes, and cardiovascular diseases.
Two other aspects of the research were noted.

First, the authors reported that the “saturation hypothesis” was supported. The connection between PSA levels and testosterone was only present when men’s testosterone levels were lower than average. For men with normal testosterone levels, the relationship was not as clear.
In this study, PSA levels did not rise substantially when total testosterone levels were above 8 nmol/L.

“It might be inferred that [testosterone] therapy in men with values above this point would not be expected to result in a rise in PSA, whereas men with [testosterone] values below this point may very well experience a rise in PSA,” the authors wrote.

Second, age appeared to play a role in the applicability of the findings. Using PSA levels to predict low testosterone was more accurate in younger patients.

“The efficacy of PSA, as a ‘screener’ for hypogonadism is modest and decreases as a function of aging, when PSA levels are affected by other factors, besides androgen activity,” the authors explained.

The study was published online in July in the Journal of Sexual Medicine.

Resources
The Journal of Sexual Medicine
Rastrelli, Giulia, MD, et al.
“Serum PSA as a Predictor of Testosterone Deficiency”
(Full-text. First published online: July 16, 2013)
http://onlinelibrary.wiley.com/doi/10.1111/jsm.12266/abstract
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