Researchers reveal new type of sweat test for better CF diagnosis

Cystic fibrosis (CF) is an incurable genetic disease in which patients have chronic lung infections. The sooner CF is diagnosed, the better the symptoms can be managed. But current tests can give ambiguous results that do not reflect disease progression. Today, in ACS Central Science, researchers reveal a new type of sweat test that can overcome this challenge.

Patients with CF have a genetic mutation that promotes mucus buildup and enables biofilms to form in their lungs, leading to frequent lung infections and breathing difficulty. In addition, chloride ions accumulate in these patients, and they excrete this as a "salty" sweat. Physicians have used this interesting effect to develop a sweat test for CF diagnosis. However, the test does not provide any staging or prognostic information and often fails in borderline cases. Most people with the gene (more than 70 percent) are "carriers" who don't develop the disease, so a genetic test alone is also not sufficient to diagnose CF. Philip Britz-McKibbin and colleagues hypothesized that there could be other molecules found in sweat that would provide the basis for a better test.

The researchers profiled the chemical composition of sweat from screen-positive infants including both unaffected carriers and confirmed CF cases. They identified several unknown chemicals in sweat that were consistently associated in babies who had CF, in addition to chloride. The researchers suggest that testing for these alternative molecules could be done for cases in which the chloride sweat test is too close to call. They also intend to track the progression of CF and monitor treatment responses to therapy in children using these and other sweat molecules.​