Cystic fibrosis diagnosed after age 13. Twenty-five teenage and adult patients including three asymptomatic men.

Cystic fibrosis was diagnosed after age 13 in 25 patients. All had an elevated sweat chloride and either a sibling with cystic fibrosis or typical pulmonary infection or digestive symptoms caused by exocrine pancreatic deficiency. Fourteen had long-standing pulmonary or digestive symptoms. In contrast, four of eight patients whose symptoms began after age 13 presented with biliary cirrhosis. Three male patients were asymptomatic at diagnosis. Opacification of all paranasal sinuses was found in all patients examined radiologically. At diagnosis, pulmonary-function testing showed obstructive changes in 19 patients and sputum cultures showed Pseudomonas aeruginosa in 15 patients. Delayed menarche in five of seven female patients and infertility in the asymptomatic male patient (two of whom were found to have aspermia) could have led to earlier diagnosis. Teenagers and young adults with long-standing pulmonary or digestive symptoms, unexplained cirrhosis, aspermia, or a sibling with cystic fibrosis should be sweat-tested by pilocarpine iontophoresis.