Exercise Intolerance, Malnutrition, Abnormal Sweat Chloride Levels, and Two CFTR Mutations: Is It Cystic Fibrosis?

New insights in pediatrics in 2021: choices in allergy and immunology, critical care, endocrinology, gastroenterology, genetics, haematology, infectious diseases, neonatology, neurology, nutrition, palliative care, respiratory tract illnesses and telemedicine

“…Cimbalo et al have tried to explain the reason of this [ 207 ], discriminating false positive and false negative sweat test results into 3 categories, i.e., ‘‘likely’’, ‘‘probable but needs validation,’’ and ‘‘unlikely’’ results based on the number of cases reported and use of genetic testing to exclude CF. They concluded that clinicians must aware the possibility of other conditions, such as adrenal insufficiency, even if two CFTR mutations are identified [ 208 ]. They also recommend repeating the sweat test and/or genetic analyses twice, possibly in specialized laboratories [ 209 ].…”

Elevated sweat chloride test: is it always cystic fibrosis?

“…Furthermore, a variety of diseases other than CF can be associated with elevated sweat chloride) even if for most conditions only few cases have been described [10][11][12], and few data are available to define if this alteration is transient or persistent. Although many of these disorders have clinical manifestations different from CF, the risk of misdiagnosis is still present [13]. Thus, in all patients with altered ST it is mandatory to know and exclude the main causes of a false positive result, particularly in patients that have symptoms that overlap between CF and other diseases.…”