S4506 Diarrhea with Depression: Sertraline-Induced Microscopic Colitis

Introduction: Microscopic colitis (MC) is a rare chronic colitis of unknown etiology, associated with inflammation triggered by infections, toxins, or drugs. Studies show selective serotonin reuptake inhibitors (SSRIs), particularly sertraline, are high-risk for MC. Case Description: A 62-year-old woman presented with 6 weeks of watery diarrhea and abdominal cramping. History included chronic obstructive pulmonary disease, smoking, mood disorder, and remote gastric ulcers, Helicobacter pylori, and Clostridioides difficile. She reported 8-10 non-bloody, watery stools daily, with pain improving after defecation. Two months ago, she had switched from duloxetine to sertraline 100 mg for uncontrolled mood symptoms without psychiatric consultation. An exam showed a tender lower abdomen and hyperactive bowel sounds. Cologuard 2 years ago was negative. Labs on admission showed normal hemoglobin, MCV 100.6, K+ 2.7, AST 46; white blood cell count, serum magnesium, and lipid panel were normal. X-Ray abdomen and computed tomography arterial portography from 2 weeks ago ruled out acute pathology. Stool studies ruled out C. difficile and parasites. Gastroenterology (GI) evaluation included a negative esophagogastroduodenoscopy and colonoscopy showing a colonic polyp (benign tubular adenoma), internal hemorrhoids, and a biopsy-proven MC and peptic duodenitis. H. pylori and dysplasia were ruled out. MC was attributed to sertraline, which was discontinued. She was treated with budesonide, cholestyramine, loperamide, and dicyclomine, and was discharged with GI and psychiatry follow-up. Complete resolution of symptoms was noted at 4 weeks. Discussion: Drug-induced MC shows a temporal association with drug initiation, symptom onset, and improvement upon cessation. Although SSRIs are high-risk, only 3 prior cases of sertraline-induced lymphocyticand collagenous MC are reported. MC presents with chronic watery diarrhea, incontinence, nocturnal symptoms, fatigue, and malnutrition. It typically affects middle-aged women and smokers. The diagnostic gold standard is a colonoscopy with biopsy. Treatment involves avoiding triggers and anti-inflammatory therapy, with budesonide as first-line. Our patient's sertraline use, normal labs/stool studies, and chronic diarrhea raised concerns for drug-induced MC. Biopsy confirmed lymphocytic colitis. Per guidelines, sertraline was held, and budesonide, loperamide, cholestyramine, and dicyclomine were started. Symptoms resolved at 4 weeks. Since sertraline is a commonly used and well-tolerated first-line agent for mood disorders, clinicians should suspect MC in patients with chronic diarrhea after starting it. Discontinuation and close follow-up to monitor for relapses are key to management.