The diagnosis of "classical" cystic fibrosis can be made based on specific criteria.


Criteria for Classical Cystic Fibrosis


One or more of the following

(1) typical pulmonary manifestations

(1a) thick mucinous secretions with chronic cough and chronic obstructive lung disease

(1b) recurrent and persistent infections, especially with Pseudomonas (often mucoid strain of Pseudomonas aeruginosa) or Staphylococcus

(2) typical gastrointestinal manifestations

(2a) pancreatic insufficiency associated with steatorrhea and failure to thrive

(2b) neonatal meconium ileus

(2c) rectal prolapse in children

(3) a history of cystic fibrosis in the immediate family




One or both of the following:

(1) a sweat chloride concentration > 60 mEq/L

(2) pathologic CFTR mutations on both chromosomes


Problems in Diagnosis


nonclassical phenotype of cystic fibrosis


patients with a compatible clinical syndrome but normal sweat chloride


patients with persistently high sweat chloride level without explanation, without clinical features of cystic fibrosis and without a family history


Other conditions associated with elevated sweat chloride:

(1) adrenal insufficiency

(2) pseudohypoaldosteronism

(3) hypothyroidism

(4) hypoparathyroidism

(5) nephrogenic diabetes insipidus

(6) ectodermal dysplasia

(7) glycogen storage disease (type I)

(8) mucopolysaccharidoses

(9) fucosidosis

(10) malnutrition

(11) Mauriac's syndrome

(12) familial cholestatic syndrome

(13) pancreatitis

(14) prostaglandin E1 administration

(15) hypogammaglobulinemia


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