‘CFTR dysfunction may be a lot more common’ in healthy young adults
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Key takeaways:
- Sweat chloride values ranging from 30 mEq/L to 59 mEq/L were observed in “a surprisingly high proportion of healthy young adults.”
- Their lung function was comparable to adults with normal sweat chloride levels.
WASHINGTON — Among healthy young adults, 28% had intermediate sweat chloride levels, with lung function measures similar to those with normal levels, according to a poster presented at the American Thoracic Society International Conference.
“We found a surprisingly high proportion of healthy young adults with sweat chloride levels in the intermediate or borderline range, suggesting that cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction may be a lot more common in the normal population than we expect,” Allen J. Dozor, MD, professor of pediatrics and clinical public health at New York Medical College, told Healio.
In a single center, prospective, cross-sectional study, Dozor and colleagues analyzed 90 healthy adults (median age, 27 years; 40% men) who underwent sweat chloride testing to evaluate how frequent intermediate sweat chloride levels (30 mEq/L to 59 mEq/L) are in this study population and how it changes lung function.
To analyze lung function changes, researchers used the multiple breath nitrogen washout technique to collect adults’ spirometry pre- and post-bronchodilator and estimate lung clearance index, according to the poster.
Of the total cohort, 21 mmol/L was the median sweat chloride value. Researchers found intermediate sweat chloride values (median, 36 mmol/L) in 25 adults (28%), of which 15 (60%) were men.
“Intriguingly, the proportion of males with elevated sweat chloride dysfunction is significantly higher than of females, although I must caution that this is a small pilot study that should be repeated in a much larger population, and importantly, in an older population,” Dozor told Healio.
Between adults with normal sweat chloride and adults with intermediate sweat chloride, measures of lung function were comparable, such as median pre-bronchodilator FEV1 percent predicted (100 vs. 99), median pre-bronchodilator FEV1/FVC (0.84 vs. 0.83) and median lung clearance index (6.3 vs. 5.7), according to the poster.
“We did not see a relationship between these results and measurements of pulmonary function in such a young cohort, but perhaps this will prove to be different in larger studies and in older adults,” Dozor told Healio.
Further, researchers reported that assessment of median sweat chloride values within the intermediate sweat chloride group of the top quartile against the bottom quartile revealed that a threshold effect was not present.
“We need to learn if these results are replicated in larger multicenter studies, including in as many diverse populations as possible, as this was just at one site, and in older adults,” Dozor told Healio. “This could be enormously important. If these results are borne out in larger studies, this could suggest that CFTR dysfunction could play an important role in the development of COPD.”