Low testosterone therapy in older men a shot in dark

The controversial use of testosterone replacement therapy in men with age-related declines in levels of the hormone lacks clear definitions, the Canadian authors of a new review say.

Difficult to diagnose and prescribe testosterone replacement in older men based on data from younger men

The controversial use of testosterone supplements by aging men is not based on clear evidence, the Canadian authors of a new review say.

Testosterone hormone replacement therapy is popular among older men who use it to treat low sex drive, lack of energy and other symptoms that can be blamed on aging.

But those prescriptions are based on comparisons with hormone levels in younger men, which means doctors lack a clear standard of what constitutes "normal" in men over 40.

Hypogonadism in males is based on low levels of testosterone in the blood and low sperm count along with signs and symptoms such as delayed sexual development, impaired sexual function, less facial and body hair, small testes and low bone mineral density.

Testosterone replacement improves symptoms of hypogonadism among young men, which can be caused by pathology in the testes or pituitary disorders. 

After the age of 30, testosterone levels decrease about 1.5 per cent a year.

But doctors have less to go on to guide their decisions to prescribe testosterone in older men.

An advisory committee from the U.S. Food and Drug Administration recently said "benefit and safety of these medications have not been established for the treatment of low testosterone levels due to aging, even if a man's symptoms seem related to low testosterone."

The regulatory group said it would require manufacturers to add warnings to the drug's label about a possible increased risk of heart attacks and strokes in patients taking testosterone.

Against this backdrop, researchers in Canada and the U.S. checked into the accuracy of using signs and self-reported symptoms to diagnose low testosterone in older men.

Dr. Adam Millar, an endocrinologist at Mount Sinai Hospital, and his co-authors, systematically reviewed 40 studies on hypogonadism in men with an average age of 40.

Look at other reasons for symptoms

Estimated prevalence varied widely, from 2 per cent to 77 per cent, they said in Monday's issue of the Canadian Medical Association Journal

"When we looked at the relationship between signs and symptoms with testosterone levels in these men, we found the relationship was actually quite weak," Millar said in an interview. 

"What this means is that men over 40 who have symptoms like erectile dysfunction or low sex drive could have many other reasons for their symptoms beyond low testosterone. As an example, a man with erectile dysfunction, it could be related to poorly controlled diabetes."

Testosterone replacement therapy is available in pill, patch or shot form.

Given the findings, Millar said physicians may need to reconsider how they diagnose the condition in older men. He recommends all clinicians take a comprehensive approach when men bring up concerns. It's an opportunity to revisit their overall health and medications. 

"Maybe different threshold levels for testosterone should be considered in men over the age of 40. I think that really speaks to need for good, high-quality studies that can address that question in more detail."

As a first step, the U.S. Centers for Disease Control and Prevention is leading a project to help standardize testosterone measurements.

With files from CBC's Amina Zafar