Diagnostic Challenge of Congenital Chloride Diarrhea and Ulcerative Colitis Overlap in an Adult Misdiagnosed with Bartter Syndrome: Case Report and Literature Review.

BACKGROUND Congenital chloride diarrhea (CCD) is an autosomal recessive disease that is usually diagnosed in early childhood. Mutations in the SLC26A3 gene have been attributed to the primary etiology of disease development. Patients with CCD usually present with electrolyte disturbances, metabolic alkalosis, and chronic diarrhea. Early diagnosis is essential to prevent long-term complications that often require genetic testing. Bartter syndrome is another congenital disorder that has clinical features similar to CCD, which might cause a delay in diagnosis in a few patients. CASE REPORT We describe the case of a 28-year-old man who was misdiagnosed as having Bartter syndrome when he was 5 months old based on the clinical features of hypokalemia, metabolic alkalosis, and a family history of Bartter syndrome. He had multiple admissions with diarrhea and was diagnosed with ulcerative colitis. Unfortunately, the course was complicated by renal failure, and the patient underwent a kidney transplant. Persistent metabolic alkalosis with diarrhea after transplantation was unusual in Bartter syndrome. Therefore, his primary diagnosis was challenged and suspicion of CCD was raised, which was confirmed by genetic testing. CONCLUSIONS CCD is a rare congenital disorder that requires high clinical suspicion and often a genetic test to confirm diagnosis. Here, we report a patient who was misdiagnosed as having Bartter syndrome until early adulthood owing to several misleading factors. We hope by reporting this case it will raise awareness about CCD in high-prevalence areas and the importance of early diagnosis to prevent serious complications.