Failure to Recognize the Association of Cystic Fibrosis and Metabolic Alkalosis

While cystic fibrosis (CF) is caused by mutations of the gene encoding the cystic fibrosis transmembrane conductance regulator protein, the defective function of this one protein can cause protean clinical manifestations. This report describes an infant with CF who presented with a persistent metabolic alkalosis, hypoelectrolytemia, recurrent vomiting, and failure to thrive. Failure to consider CF allowed the progressive development of renal, metabolic, and neurodevelopmental problems. These were secondary manifestations of CF, but they led physicians diagnostically further afield. By the time CF was diagnosed at 32 months of age, the infant had been evaluated by 11 pediatric subspecialties at three pediatric tertiary care centers. CF treatment resulted in marked improvement or complete resolution of her clinical problems. Recognition of the association of CF and metabolic alkalosis and the routine use of a sweat test in unexplained failure to thrive still need to be emphasized in pediatric education and care.