Low testosterone levels found in one-quarter of CF men: Study
But researchers say standardized measures are needed for hormone testing
About one-quarter of men with cystic fibrosis (CF) have low testosterone levels, according to a new study that sought to assess the prevalence of this sexual health issue in males with the genetic disease.
Neither age nor the time of day when testosterone measurements were taken influenced the levels of the male sex hormone in these patients, the data showed. Testosterone levels were found to correlate with patients’ levels of hemoglobin — the protein that carries oxygen in red blood cells.
Low testosterone, known as hypogonadism, in men with CF has been linked to reproductive problems and other issues such as bone and muscle health. But little standard testing has been established to date for determining hypogonadism in male CF patients.
“The increasing data on the prevalence of hypogonadism in males with cystic fibrosis stresses the need for standardizing the measurement of testosterone in all male patients with CF,” the researchers wrote.
The study, “Testosterone concentrations and associated predictors in men with cystic fibrosis: a retrospective, single-center study,” was published in The American Journal of Medical Sciences.
Lack of testing measures for low testosterone levels in CF men
CF is caused by mutations in the CFTR gene, leading to no or faulty production of the CFTR protein that normally regulates the flow of chloride, a salt, through the cell membrane. This results in thick and sticky mucus accumulation in several organs, particularly the lungs and organs of the digestive and reproductive systems.
Males with CF may experience reproductive issues that include delayed puberty, problems with fertility, and hypogonadism. Infections and inflammation, the use of glucocorticoids, and low CFTR protein levels in cells that regulate the function of the reproductive system have all been associated with causing hypogonadism.
However, “the prevalence of hypogonadism in males with CF is largely under-studied despite its impact on bone health, muscle function, and quality of life,” the researchers wrote.
In this study, scientists at Emory University in Atlanta led a team that assessed the prevalence of low testosterone levels in men with CF. Their work involved 69 men followed at the university’s CF Center between 2016 and 2023.
The men had a mean age of 33.3 years, and all participants had at least one testosterone measurement at any point in the study. A level of 300 nanograms (ng)/dL or lower in these men was defined as low testosterone. More than two-thirds of participants had only one testosterone measurement, though 20 had several measurements during the study.
Data showed that 27.5% of the patients, or slightly more than one-quarter, had low testosterone levels.
Since a diagnosis of hypogonadism requires two low testosterone measurements, we could not confirm clinical hypogonadism for many of the study participants since the majority (59%) had only a single measurement of testosterone.
However, the researchers noted that the lack of standard measures for testosterone hampered their ability to confirm a diagnosis for more than half of the study’s participants.
“Since a diagnosis of hypogonadism requires two low testosterone measurements, we could not confirm clinical hypogonadism for many of the study participants since the majority (59%) had only a single measurement of testosterone,” the researchers wrote.
Testosterone levels in CF men also linked to hemoglobin
Among all patients, the latest mean testosterone level was 421.1 ng/dL, according to the researchers.
Most patients (63%) had their measurements done after 10 a.m., which means after the recommended time frame. However, the researchers found no statistically significant differences in testosterone levels measured before and after 10 a.m.
“Time of day of measurement did not seem to influence testosterone concentrations and thus may not need to be standardized during the initial clinical assessment of hypogonadism, particularly if current screening rates are already low,” the researchers wrote. This means that “screening for low testosterone may be conducted whenever possible with repeat confirmatory testing of testosterone performed for low measurements.”
Other clinical variables also were determined in the study. The mean level of hemoglobin was 14.23 g/dL, which was within the normal range.
Further statistical analysis revealed that testosterone levels correlated significantly with hemoglobin levels.
In that regard, “androgens, such as testosterone, stimulate the release of erythropoietin [a hormone that drives the production of red blood cells], which aids in maintaining constant blood hemoglobin levels,” the researchers wrote.
Similar to the time of day when testosterone was measured, the patients’ age did not correlate with testosterone levels.
Interestingly, the lack of correlation between testosterone levels and age represents “different findings from previous studies,” according to the researchers. They noted that other studies found that testosterone levels generally decline throughout life.
Overall, the team noted that, while the findings of this work shed light on the prevalence of low testosterone levels in men with CF, more research still is needed.
“Future studies should aim to … assess rates of hypogonadism and identify associated risk factors,” the team concluded.
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