Uncommon Presentation of Cystic Fibrosis: A Case Report and Literature Review.

Cystic fibrosis (CF) is a multiorgan disease, caused by autosomal recessive (AR) mutations in the cystic fibrosis transmembrane regulator (CFTR) acting primarily as a chloride channel. CF is most commonly diagnosed in Caucasian populations. Common clinical presentations in pediatric patients include chronic cough, respiratory tract infections such as pneumonia, digestive symptoms, and stunted growth, and malnutrition due to gastrointestinal malabsorption and pancreatic insufficiency. Excessive sweat sodium chloride losses due to dysfunctional sweat glands in CFTR result in volume contraction and secondary hyperaldosteronism leading to renal potassium losses and metabolic alkalosis. Hypokalemic hypochloremic metabolic alkalosis is a known but uncommon presenting sign of the disease, documented as pseudo Bartter syndrome. Common mutations in the CFTR gene are now included in prenatal genetic screening programs. We describe the case of an infant of African descent with normal prenatal screening who presented with severe hypokalemic hypochloremic metabolic alkalosis and was diagnosed with CF with further genetic confirmation of the diagnosis.