Diagnosis of cystic fibrosis: Indian perspective

Cystic fibrosis (CF) is one of the common life limiting inherited diseases in Caucasian population. Recent reports suggest that the diagnosis of cystic fibrosis in Indian children is missed or delayed due to low index of suspicion. The diagnosis of cystic fibrosis is suspected by the typical clinical features and should be confirmed by doing sweat chloride estimation. If sweat test is not available, ancillary tests including blood electrolyte and acid base balance, airway microbiology, tests to identify pancreatic insufficiency and semen analysis for obstructive azoospermia in post pubertal boys should be carried out. Positive results of these tests make the suspicion very strong. A strongly suspected case should be treated as cystic fibrosis, but for giving a diagnosis of CF, sweat test should be done from the nearest centre where it is available. In the presence of typical clinical features with borderline sweat chloride values sweat test should be repeated 2-3 times and the child should be investigated for alternative diagnosis. In the absence of alternative diagnosis with consistently high or borderline sweat chloride values an attempt should be made to get tests for mutations.