Cystic fibrosis (CF) is an autosomal recessive disorder affecting children, which is characterized by (1) chronic pulmonary disease, (2) deficient exocrine pancreatic function, and (3) other complications of inspissated mucus in a number of organs, including the small intestine, the liver, and the reproductive tract. The diagnosis of CF is most reliably made by the demonstration of increased concentrations of electrolytes in the sweat. The decreased chloride conductance characteristic of CF results in a failure of chloride reabsorption by the cells of the sweat gland ducts and, hence, to the accumulation of sodium chloride in the sweat. All of the pathologic consequences of CF can be attributed to the presence of abnormally thick mucus. Lack of pancreatic enzyme secretion in patients with CF causes malabsorption and foul-smelling fatty stools (steatorrhea). The other choices do not address the underlying cause of malabsorption in patients with CF.Diagnosis: Cystic fibrosis