A blood test alone is not enough to diagnose low testosterone levels in men, and it should be used in tandem with a physical exam, a panel of experts says.
The number of men in the United States diagnosed with low testosterone has increased significantly over the last decade, they noted. However, inconsistent laboratory practices and other problems result in unreliable blood test results for the condition. Testosterone is the major male sex hormone.
The lack of consistency in laboratory practices occurs in areas such as blood-sample collection and storage and the methods used to analyze blood samples.
The panel of doctors from six major U.S. institutions analyzed data from more than 10,000 patients. Their findings were published online March 6 ahead of print in the May issue of the journal Urology.
"In some cases, testosterone levels, tested on the same day from a blood sample taken from a single patient, differed by as much as 30 percent from one lab to the next," said study author Dr. Darius Paduch, a urologist and male sexual medicine specialist at NewYork-Presbyterian/Weill Cornell Medical Center in New York City, said in a medical center news release.
The findings indicate that relying on blood test results alone can lead to both under- and over-treatment of low testosterone levels in men.
Paduch said "it's critical to primarily focus on treating the patient and his symptoms," while using blood test results as a "secondary guideline."
Symptoms of low testosterone levels -- also known as hypogonadism -- include fatigue, loss of sexual desire and erectile dysfunction. The condition is widely regarded as something that affects men aged 65 and older, but it's increasingly being diagnosed in younger men with diabetes and obesity.
Doctors and other health care providers should insist that labs follow standardized guidelines for testosterone testing issued by the U.S. Centers for Disease Control and Prevention, Paduch said.