Chronic Diarrhea and Weight Loss in an 18-month-old Boy.

1. Kathleen Lo, MD* 2. Sunita Sridhar, MD* 3. Sabina Ali, MD† 1. *Department of Pediatrics and 2. †Department of Pediatric Gastroenterology, University of California San Francisco Benioff Children’s Hospital Oakland, Oakland, CA An 18-month-old boy presents to the emergency department with a 3-month history of diarrhea and 1 month of weight loss. He was in his usual state of health until 3 months earlier when he began having liquid stools approximately 4 times a day. The stools have increased in frequency, and at the time of presentation he is having up to 20 stools per day. They are reported to be watery, nonbloody, and nonfrothy. Parents deny fever, sick contacts, recent travel, or ingestion of raw meat or unpasteurized dairy products. Oral intake has been unchanged; he eats a varied diet that includes small amounts of juice and occasional cow milk. He was seen by his pediatrician 2 months earlier for a similar complaint and was trialed on a lactose-free diet without improvement. Stool testing was negative for ova and parasites, Giardia, and fecal occult blood. Physical examination is notable for a well-appearing but thin toddler with extremity wasting. His weight is 22.3 lb (10.1 kg) (8th percentile), down from 26.5 lb (12 kg) (72nd percentile) 10 weeks ago. He is afebrile with normal vital signs, moist mucous membranes, and normal skin turgor. His abdomen is distended but soft, without appreciable mass or hepatosplenomegaly. He has an erythematous diaper rash surrounding the gluteal cleft. The remainder of his examination findings are normal. Initial laboratory tests are significant for a serum sodium level of 129 mEq/L (129 mmol/L), potassium level of 2.2 mEq/L (2.2 mmol/L), chloride level of 94 mEq/L (94 mmol/L), and bicarbonate level of 12 mEq/L (12 mmol/L). Complete blood cell count, C-reactive protein level, and erythrocyte sedimentation rate are normal. Human immunodeficiency virus screen, celiac antibody profile, and gastrointestinal viral panel are negative. Stool culture grows normal flora. Abdominal radiograph is normal, and upper and lower endoscopy is grossly normal. …