A 32-year-old woman comes to the emergency department with her boyfriend for evaluation of diarrhea for the past 3 weeks. The patient works as a schoolteacher and says, "There was a stomach bug going around recently, but no one else has had symptoms for this long." She reports voluminous and watery bowel movements that occur 10-12 times a day. She feels fatigued and weak and states that her sleep has been disrupted a few times due to nocturnal bowel movements. The patient has no abdominal pain, melena, hematochezia, vomiting, or unexplained weight changes. Her boyfriend reports that she had a similar episode of diarrhea 2 months ago; laboratory evaluation and colonoscopy showed no abnormalities, and the patient's symptoms resolved a few days later. Temperature is 37 C (98.6 F), blood pressure is 120/80 mm Hg, and pulse is 84/min. There are no orthostatic changes. Mucous membranes are moist, and capillary refill is normal. Abdominal examination shows mild tenderness to palpation in all 4 quadrants, with no rebound tenderness, guarding, or rigidity. Complete blood count, serum chemistry, liver function tests, and urinalysis are normal. HIV testing is negative. Fecal occult blood is negative. Which of the following is the most appropriate next step in management of this patient?

Question

A 32-year-old woman comes to the emergency department with her boyfriend for evaluation of diarrhea for the past 3 weeks.  The patient works as a schoolteacher and says, "There was a stomach bug going around recently, but no one else has had symptoms for this long."  She reports voluminous and watery bowel movements that occur 10-12 times a day.  She feels fatigued and weak and states that her sleep has been disrupted a few times due to nocturnal bowel movements.  The patient has no abdominal pain, melena, hematochezia, vomiting, or unexplained weight changes.  Her boyfriend reports that she had a similar episode of diarrhea 2 months ago; laboratory evaluation and colonoscopy showed no abnormalities, and the patient's symptoms resolved a few days later.  Temperature is 37 C (98.6 F), blood pressure is 120/80 mm Hg, and pulse is 84/min.  There are no orthostatic changes.  Mucous membranes are moist, and capillary refill is normal.  Abdominal examination shows mild tenderness to palpation in all 4 quadrants, with no rebound tenderness, guarding, or rigidity.  Complete blood count, serum chemistry, liver function tests, and urinalysis are normal.  HIV testing is negative.  Fecal occult blood is negative.  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

Explanation: This patient has normal vital signs, physical examination, laboratory results, and colonoscopy findings but reports persistent, voluminous diarrhea, raising suspicion for factitious diarrhea. Factitious disorder is characterized by intentional falsification of illness in the absence of external reward (eg, financial compensation, disability benefits). Patients with factitious diarrhea purposely cause large, voluminous stools, most commonly by improper use of laxatives; however, they can also create the appearance of diarrhea by adding fluid to the stool. Therefore, helpful tests in evaluating factitious diarrhea include: Factitious disorder Stool osmolality: Stool osmolality is in equilibrium with plasma osmolality and typically remains constant (eg, 290 mOsm/kg) in organic gastrointestinal disease. Hypoosmolality suggests addition of water or other dilute fluid; hyperosmolality suggests addition of a concentrated fluid (eg, urine). Stool electrolytes: Elevated stool magnesium or phosphate levels suggest overuse of saline osmotic (ie, magnesium- or phosphate-containing) laxatives. Stool osmotic gap: Osmotic laxatives (eg, lactulose, polyethylene glycol) cause a high osmotic gap diarrhea, whereas senna and bisacodyl produce a low osmotic gap secretory diarrhea. (Choice A) Tissue transglutaminase IgA antibodies are seen in celiac disease, which is a common cause of chronic diarrhea. However, patients typically have additional findings, such as weight loss and signs of malabsorption (eg, iron deficiency anemia, vitamin D deficiency with hypocalcemia). (Choice B) An abdominal CT scan may identify colitis (eg, colonic wall thickening, fat stranding) in patients with diarrhea; however, it is less sensitive than a colonoscopy, which was unremarkable in this patient. (Choice C) The lactose hydrogen breath test can diagnose lactose intolerance, which causes postprandial abdominal discomfort and diarrhea. However, the bowel movements would be triggered by meals and do not typically awaken patients from sleep. (Choice E) Norovirus can cause chronic diarrhea in immunocompromised patients (eg, HIV, solid-organ transplant), but symptoms are typically brief (eg, 1-2 days) and self-limited in immunocompetent individuals. Educational objective: Diarrhea that is not explained after extensive evaluation suggests possible factitious diarrhea. Helpful studies include stool osmolality (hypoosmolality suggests addition of water or dilute fluid; hyperosmolality suggests addition of concentrated fluid [eg, urine]), stool electrolytes (elevated magnesium or phosphate suggests use of saline osmotic laxatives), and stool osmotic gap (osmotic laxatives cause a high osmotic gap diarrhea). References: Features associated with laxative abuse in individuals with eating disorders. (http://www.ncbi.nlm.nih.gov/pubmed/16738081) Brief report: factitious diarrhea detected by measurement of stool osmolality. (http://www.ncbi.nlm.nih.gov/pubmed/8159195) Evaluating the patient with diarrhea: a case-based approach. (http://www.ncbi.nlm.nih.gov/pubmed/22677080)

A 32-Year-Old Woman Comes to the Emergency Department with Her