New Lower-Cost Diagnostic Test for Cystic Fibrosis

A new diagnostic test for cystic fibrosis has been developed, which measures chloride levels in a patient’s sweat. The diagnostic uses a fluorescent dye to allow clinicians to detect high levels of chloride, which could be indicative of cystic fibrosis.

Cystic fibrosis affects an estimated 30,000 Americans, and is caused by the inheritance of two mutated copies of gene which controls the transport of chloride ions into, and out of, cells. While there is currently no cure for the disease, early diagnose can allow for the management of symptoms.

Measuring chloride levels in sweat samples has been a common way to diagnose cystic fibrosis, however this method currently requires a technician to perform a labor-intensive manual titration. This diagnostic procedure is costly, and is subject to human error and can result in false negatives.

In the current research – supported by the Nation Institutes of Health (NIH) – researchers at Pennsylvania State University have developed a diagnostic in which a fluorescent dye deteriorates in the presence of high chloride levels. The research was published in the journal, Chemical Science.

“This is an important step towards faster, more reliable diagnosis,” said Dr. Seila Selimovic, program director of the National Institute of Biomedical Imaging and Bioengineering, part of the NIH. “The new sensing technology is cheap and easy to apply and, if used as part of a point-of-care device may allow more clinics to provide early cystic fibrosis tests. That is a great thing for the developed world, but is a game changer for the economically developing world, since early intervention can save lives in dealing with this devastating and all too common disease.”

To develop the diagnostic test, the researchers used a citrate-based dye that emits diminishing levels of fluorescent light in the presence of rising concentrations of chloride. When this diagnostic was compared to the method currently used in clinical practice, the researchers found that both methods yielded similar results.

What’s more, the fluorescent diagnostic was able to detect a wider range of chloride concentrations, compared to the conventional method. In addition, because this diagnostic is automated, it removes the issue of human error, potentially leading to more accurate diagnosis.

“We are stepping into the point-of-care device – this kind of low cost, easy to use, home-use device,” said Dr. Jian Yang, professor of biomedical engineering at Pennsylvania State University, and senior author of the paper. “That can really make the detection of the sweat, or even some other biological fluids like urine or serum, much easier in the future because everyone can use it.”