Congenital chloride diarrhea misdiagnosed as Bartter syndrome.

Congenital chloride diarrhea is the most frequent secretory-type diarrhea during the infantile period in the presence of normal intestinal mucosa. The disease has an autosomal recessive inheritance. Although approximately half of the reported cases to date are from Finland, a much higher incidence has been reported among Arabic people. The defective gene is SLC26A3, which encodes a Na-independent CL/HCO3 exchanger that is expressed primarily in the apical brush border membrane of ileal enterocytes and colonic epithelium. The disease is characterized by dehydration and hypochloremic metabolic alkalosis. Bartter syndrome, cystic fibrosis and pyloric stenosis also lead to similar electrolyte disturbances in the early neonatal period. The diagnosis of congenital chloride diarrhea can be confirmed by measuring the fecal concentration of Cl, which always exceeds 90 mmol/L in patients with normal water and electrolyte balance. Here, we report a patient with congenital chloride diarrhea misdiagnosed as Bartter syndrome until 20 months of age.