Low T common, but likely underdiagnosed, in men with CF

Researchers cite the need for more testing for the hormone testosterone

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Men with cystic fibrosis (CF) commonly have low testosterone levels, though this is likely underrecognized due to a lack of testing, a new study highlights.

The findings underscore the importance of checking testosterone levels in men with CF so that interventions can be discussed if warranted, researchers said in the study “Prevalence of Low Testosterone in Men with Cystic Fibrosis and CBAVD: a cross-sectional study using a large, multi-institutional database,” which was published in Urology.

Infertility is a common symptom of CF in men. Specifically, most men with CF are born with congenital bilateral absence of the vas deferens (CBAVD), a condition in which tubes that normally transport sperm from the testes are absent.

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People with CBAVD usually have normal sperm production in the testes, but because the sperm cannot be transported from the testes into ejaculatory fluid, they cannot conceive via sexual intercourse.

Testosterone, often abbreviated as simply ‘T,’ is the main hormone that controls male sexual development. Low levels of testosterone — defined as less than 300 nanograms per decaliter (ng/dL) — can contribute to issues including mental health problems and sexual dysfunction.

In this study, researchers set out to examine the prevalence of low T in men with CF and/or CBAVD.

“Low T is of special interest in this population due to the important role of T in development and maintenance of muscle mass and bone health which are related to poorer long-term prognosis in patients with chronic diseases including CF,” the researchers wrote.

The TriNetX healthcare database

Using a large healthcare database called TriNetX, the researchers identified data for more than 14,000 men with CF. About three-quarters of the patients were white, and the mean age was 44.

Only about one in 10 of these men with CF had a documented test of T levels. For these individuals, the mean T level was 337 ng/dL, which is within the normal range. But nearly one-third (32.7%) of the men had low T.

Of the men with low T, most (59.3%) were treated with supplemental testosterone therapy.

The database also included data on 3,439 people with CBAVD, of whom 8.9% had a documented test of T levels. Among CBAVD patients with available T tests, 43% had low T, most of whom were getting supplemental testosterone treatment.

“Our work also demonstrates a higher than anticipated prevalence of low T showing one third of men with CF and nearly half of men with CBAVD demonstrated low T which may be higher than an age-matched, healthy cohort would demonstrate,” the researchers wrote, though they noted that it’s difficult to accurately estimate how common low T is for the general population, particularly since T levels naturally vary with age.

Another notable finding from this study is that most men with CF or CBAVD did not have any documented test of T levels. While the team said it’s possible that some patients had T tests that weren’t recorded in the database, they said the findings emphasize the importance of checking T levels in people with CF.

A known risk factor for sexual dysfunction, infertility

“We found that men with a diagnosis of CF and CBAVD are under evaluated and may be undertreated for low T,” the researchers wrote, adding that low T “is a known risk factor for sexual dysfunction and infertility, thus CF providers should be aware of this data and consider earlier T testing in this population.”

The team added that testing can allow treatment to be given where it’s needed. They noted, however, that supplemental testosterone treatment carries its own risks, so it’s important for patients and providers to have detailed discussions about the potential costs and benefits of medical interventions for low T.