A 34-year-old woman comes to the office due to episodic mid-abdominal cramping pain, nausea, and watery diarrhea for the past 4-5 months. The episodes often occur within an hour of eating, and she has also experienced increased flatus and a bloating sensation. The patient takes a proton pump inhibitor for gastroesophageal reflux disease. She underwent a cholecystectomy 3 years ago due to symptomatic gallstones. She drinks alcohol on social occasions and does not use tobacco or illicit drugs. The patient jogs daily and goes to the gym 3 times a week. Over the past several months, she has been consuming more leafy green vegetables, fruits, and low-fat dairy products in an effort to lose weight. Her parents were born in China, but the patient has not traveled overseas in the past 4 years. Temperature is 36.8 C (98.2 F), blood pressure is 128/72 mm Hg, pulse is 87/min, and BMI is 30 kg/m². The abdomen is soft and nontender. Fecal occult blood test is negative. Which of the following is the most likely cause of this patient's current condition?

Question

Quizplus · Accepted Answer

This patient with chronic, crampy abdominal pain; bloating; and watery diarrhea after meals likely has lactose intolerance (LI). LI is a common cause of adult-onset diarrhea due to malabsorption and presents in adults age 20-40. It is more common among patients of African, Latin American, Asian, or Native American descent. Lactose is processed into glucose and galactose by intestinal lactase on the brush border of the duodenum, and lactase enzyme deficiency is the most common cause of LI. Symptoms occur as the osmotic load of undigested lactose passes through the intestines, drawing water into the lumen and decreasing transit time. In addition, colonic bacteria ferment lactose, creating short-chain fatty acids and hydrogen gas (bloating). LI can be established in patients who have a history of consuming several servings of lactose products and whose symptoms resolve after initiating a lactose-free diet. If the diagnosis is inconclusive (eg, atypical age or ethnicity), a lactose breath hydrogen test can be performed. Treatment consists of diet change or supplementation with lactase. (Choice B) Insufficient bile salt absorption by the terminal ileum can result in diarrhea in the immediate postoperative period after cholecystectomy, but symptoms typically resolve within a few weeks to months. (Choice C) The use of proton pump inhibitors has been associated with Clostridium difficile infections. However, C difficile infections are typically associated with acute onset of watery diarrhea and low-grade fever. Fecal occult blood testing is frequently positive. (Choice D) Celiac disease results from an autoimmune reaction to the gluten-derived peptide gliadin, which results in destruction of enterocytes and villous atrophy in the small intestine. Patients with celiac disease commonly report fatigue and foul-smelling, greasy diarrhea. (Choice E) Small intestinal bacterial overgrowth (SIBO) occurs when bacteria from the colon are inappropriately present in the small intestine. The diarrhea is frequently greasy. SIBO is usually associated with underlying motility disorders (eg, diabetes mellitus) or anatomical abnormalities (eg, jejunocolic fistula). This patient has no risk factors and no symptoms of steatorrhea (eg, loose, greasy stools), making SIBO less likely. (Choice F) Patients with exocrine pancreatic insufficiency have impaired digestion of fat and protein and symptoms of steatorrhea. However, they typically have risk factors such as chronic pancreatitis, cystic fibrosis, or a history of bowel or pancreatic resection. (Choice G) Ulcerative colitis, which results in intermittent colonic inflammation, is associated with chronic abdominal pain, bloody diarrhea, and systemic symptoms (eg, fever, fatigue). Educational objective: Lactose is processed into glucose and galactose by intestinal lactase that is present on the brush border of the duodenum. Lactase enzyme deficiency commonly causes lactose intolerance, which is characterized by chronic, crampy, postprandial abdominal pain, bloating, and watery diarrhea. References: Lactose intolerance in adults: biological mechanism and dietary management. (http://www.ncbi.nlm.nih.gov/pubmed/26393648) Lactose intolerance: from diagnosis to correct management. (http://www.ncbi.nlm.nih.gov/pubmed/24443063)

A 34-Year-Old Woman Comes to the Office Due to Episodic