Blood test poor diagnostic tool for hypogonadism

Relying on blood test results alone is insufficient for diagnosing hypogonadism, according to a recent study.

The analysis, which utilized published data from more than 10,000 patients, was published online ahead of print in Urology (Feb. 18, 2014). The initiative was spearheaded by the AUA and was conducted by a panel of physicians representing six major U.S. institutions.

The new research comes amid increased scrutiny of testosterone replacement therapy in men, including an FDA investigation of possible cardiovascular risks and, more recently, an AUA position statement and a popular consumer group’s call for a black box warning.

Among the authors’ findings was that despite advances in technology, inconsistent laboratory practices, among other issues, leads to unreliable blood test results.

"In some cases, testosterone levels, tested on the same day from a blood sample taken from a single patient, differed by as much 30% from one lab to the next," said lead author Darius Paduch, MD, PhD, of New York-Presbyterian/Weill Cornell Medical Center and Weill Cornell Medical College, New York.

Given the result of the review, Dr. Paduch notes that a stringent reliance on blood test results alone can lead to both under- and overtreatment of hypogonadism. Instead, he notes, the data demonstrate that "it's critical to primarily focus on treating the patient and his symptoms, while using the T level from a blood test as a secondary guideline." Symptoms may include fatigue, loss of libido, and erectile dysfunction.

The medical community has long questioned the reliability of blood tests to diagnose hypogonadism. What makes these latest findings significant are the stringent criteria used for the study, which included an exhaustive review of hundreds of papers, as well as input from a large multidisciplinary team of medical professional societies and clinical experts from diverse fields and representatives from government agencies and medical equipment manufacturers, according to the researchers.

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Although variable blood test results can be attributed to a host of factors, one of the biggest problems the authors found is a lack of consistency in laboratory practices-from collecting and storing blood samples to using different methods to analyze the results. To address these concerns, Dr. Paduch advises doctors and other health care providers to insist that labs follow standardized guidelines for testosterone testing issued by the Centers for Disease Control (CDC).

Dr. Paduch and his colleagues are working with the CDC to establish evidence-based T-level norms, another challenge associated with diagnosing low testosterone.

The AUA recently weighed in on the testosterone therapy debate with a position statement on the treatment. The organization said that “management of hypogonadism should start with careful evaluation by a physician experienced in diagnosing hypogonadism.”

“The diagnosis should be made only after taking detailed medical history, physical examination, and obtaining appropriate blood tests. Testosterone therapy should not be offered to men with normal testosterone levels… The AUA recognizes and encourages the need for increased educational awareness of the benefits and risks of testosterone therapy among both patients and health care providers,” the statement read.

In related news, citizen advocacy group Public Citizen has petitioned the FDA to place a black box warning regarding the increased risks of heart attacks and other cardiovascular dangers to the product labels of all testosterone-containing drugs available in the U.S.

Public Citizen said its petition is “based on growing evidence of the risks of heart attacks and other cardiovascular dangers from many individual randomized studies going back as far as 2010 and a recently published overall analysis (meta-analysis) of 27 studies going back as far as 20 years [BMC Medicine 2013; 11:108].” The group said it was also prompted by a recent study in which researchers found a twofold increase in the risk of heart attack shortly after beginning testosterone therapy in men under 65 years of age (PLOS ONE; online, Jan. 29, 2014).

“Unless the FDA immediately begins to provide strong, adequate black-boxed warnings about the risks of heart attacks and other cardiovascular diseases, the continuing toll of heart attacks, many in people who are not even candidates for testosterone, will continue. At the present rate of prescribing, almost 13,000 prescriptions a day are filled for testosterone products in this country. Each day of delay of the black box warning ensures much more exposure, too often for men who cannot benefit from the drug but will only be exposed to its risks,” Sidney Wolfe, MD, of Public Citizen said in a statement.

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