Does that child really have cystic fibrosis?.

A diagnosis of cystic fibrosis was incorrectly made after false- positive sweat 
tests in 14 children. 13 of these children had been tested 
at hospitals where it seems likely that sweat tests were not 
done very often. All the children had normal sweat-electrolyte values when 
the test was repeated at a regional paediatric centre where approximately 
250 sweat tests are done each year. In 5 cases, detailed 
testing of pancreatic function was normal. None of the children had 
typical chest disease and only 2 had gastrointestinal symptoms. In the 
absence of the typical clinical features of the disease a diagnosis 
of cystic fibrosis should be made with extreme caution and only 
after meticulous testing of both sweat electrolytes and pancreatic function. 