A 12-month-old girl is brought to the office due to diarrhea. Two weeks ago, the girl had fever, vomiting, and diarrhea with poor oral intake that lasted for 3 days, after which the fever and vomiting resolved and the diarrhea improved. The girl then resumed her regular diet, including whole milk with varied meals. She subsequently developed worsening diarrhea with no fever or vomiting. The stools occur about 3 times only during the day and are bulky and malodorous but without blood or mucus. The girl does not take any medications. Vital signs are normal. On examination, she is alert and well hydrated. Her abdomen is distended and hypertympanic. There is mild diffuse tenderness to palpation, but no rebound, guarding, or masses. Stool for occult blood is negative. Which of the following is the most likely cause of her current symptoms?

Question

A 12-month-old girl is brought to the office due to diarrhea.  Two weeks ago, the girl had fever, vomiting, and diarrhea with poor oral intake that lasted for 3 days, after which the fever and vomiting resolved and the diarrhea improved.  The girl then resumed her regular diet, including whole milk with varied meals.  She subsequently developed worsening diarrhea with no fever or vomiting.  The stools occur about 3 times only during the day and are bulky and malodorous but without blood or mucus.  The girl does not take any medications.  Vital signs are normal.  On examination, she is alert and well hydrated.  Her abdomen is distended and hypertympanic.  There is mild diffuse tenderness to palpation, but no rebound, guarding, or masses.  Stool for occult blood is negative.  Which of the following is the most likely cause of her current symptoms?

Quizplus · Accepted Answer

11ec25c8_d5fa_c10c_bc81_bb2d85eff00e_MD0003_00 This patient with a recent history of improving symptoms of gastroenteritis has worsening diarrhea after reintroducing dietary dairy. In the absence of other symptoms (eg, vomiting, fever), the most likely diagnosis is carbohydrate malabsorption due to secondary lactase deficiency. Secondary lactase deficiency is usually transient and due to epithelial damage from infection (eg, gastroenteritis) or inflammation (eg, inflammatory bowel disease [IBD]). Temporary loss of lactase, a brush border enzyme found within small intestinal mucosa, results in the fermentation of unabsorbed lactose by colonic bacteria. The hydrogen gas produced leads to the classic symptoms of crampy abdominal pain, bloating, and flatulence with a hypertympanic abdomen on examination. In addition, colonic lactose creates an osmotic influx of water into the bowel, resulting in diarrhea. Stools are often bulky and malodorous but not bloody or mucoid. Bowel movements typically occur within a few hours of lactose ingestion, making this patient's diarrhea frequency and lack of overnight symptoms consistent with the diagnosis. Treatment is temporary dietary modification with limited dairy intake. Most patients with secondary lactase deficiency do not need a diagnostic hydrogen breath test, because symptoms usually resolve within weeks as the intestinal mucosa heals. (Choice A) Bile salt malabsorption causes chronic diarrhea due to inability to digest fat. This condition is typically seen with chronic, terminal ileum inflammation (eg, IBD) and is not associated with gastroenteritis in an otherwise healthy child. (Choice C) Clostridioides (formerly Clostridium) difficile infection causes profuse, watery diarrhea typically weeks after a course of antibiotics. This infection is uncommon in young children and unlikely in this patient with no history of antibiotic use. (Choice D) Milk protein-induced proctocolitis is a non-IgE-mediated reaction that usually causes blood-streaked, mucoid stools in early infancy. This child's age and symptom onset following recent gastroenteritis make this diagnosis unlikely. (Choice E) This patient's fever, vomiting, diarrhea, and poor feeding 2 weeks ago was likely due to viral gastroenteritis. The temporal relationship of worsening diarrhea with dairy reintroduction and lack of other symptoms makes secondary lactase deficiency more likely than reinfection. Educational objective: Secondary lactase deficiency caused by intestinal epithelial damage (eg, gastroenteritis, celiac disease) leads to carbohydrate (ie, lactose) malabsorption and transient symptoms of diarrhea, crampy abdominal pain, and bloating. References: Update on lactose malabsorption and intolerance: pathogenesis, diagnosis and clinical management. (http://www.ncbi.nlm.nih.gov/pubmed/31427404) Lactose intolerance. (http://www.ncbi.nlm.nih.gov/pubmed/30335318)

A 12-Month-Old Girl Is Brought to the Office Due to Diarrhea