Question

What special test is done to confirm CF? What indicates a positive result?

a) Sweat chloride test; chloride concentration >60 mmol/L
b) Genetic testing; presence of specific mutations
c) Chest X-ray; presence of bronchiectasis
d) Pulmonary function test; decreased FEV1/FVC ratio

Answer 1

A sweat chloride test confirming a chloride concentration greater than 60 mmol/L is the specific test to diagnose Cystic Fibrosis, which is caused by a faulty CFTR protein affecting chloride ion transport.

Step-by-step explanation:

The special test done to confirm Cystic Fibrosis (CF) is the sweat chloride test. A positive result for the sweat chloride test indicates a chloride concentration greater than 60 mmol/L. This test is crucial because CF provokes the production of a faulty CFTR protein, which impairs the chloride ions transport, leading to thick, sticky mucus accumulation primarily in the lungs and also affecting other organs. Genetic testing can also be done to detect specific mutations in the CFTR gene. However, a chest X-ray showing bronchiectasis or a pulmonary function test indicating a decreased FEV1/FVC ratio could suggest lung damage due to CF but are not confirmatory tests for the genetic disorder itself.