Misdiagnosis of Cystic Fibrosis Based on Transient Pancreatic Insufficiency and Elevated Sweat Chloride

Introduction

Exocrine pancreatic insufficiency (PI) is a rare cause of dystrophy. Fecal elastase 1 (FE1) and 72-h fecal fat collection are the recommended indirect tests for pancreatic function. The most common cause of PI in children is cystic fibrosis (CF). PI is highly specific to CF and affects 85% of all CF patients (Borowitz D et al., J Pediatr 2004; 145: 322–326) Diagnosis of CF is based on confirmation of cystic fibrosis transmembrane regulator (CFTR) protein dysfunction based on a sweat chloride level of>60 mml/l on at least 2 occasions, detection of 2 CF-causing mutations, and/or an abnormal nasal potential difference measurement (NPD) (DeBoeck K et al., Thorax 2006; 61: 627–635). We report our experience with a patient who was misdiagnosed with CF based on dystrophy attributed to transient PI and transiently elevated sweat chloride.