Case Presentation: An 83-year-old female patient with a history of esophageal strictures, GERD, dysphagia, pancreatic insufficiency, hypothyroidism, and hypertension presented directly from GI clinic with four months of watery diarrhea (6-16 stools daily), profound weight loss (~40 lbs), and decreased oral intake. The patient presented to outside hospitals on several occasions and was provided symptomatic management for presumed viral infections and electrolyte repletion for hypokalemia. However, she did not improve and became diaper-dependent due to fecal urgency. The differential diagnosis was broad. Infectious etiologies were considered less likely, given the subacute nature of her persistent diarrhea and the absence of leukocytosis, blood in stool, or fever. Malignancy, such as VIPoma, was high on the differential, given her advanced age and significant weight loss. IBS, new onset IBD, microscopic colitis, worsening of her pancreatic insufficiency, and ARB-associated enteropathy were also considered. The patient did not have a family history of IBD or GI malignancy. Her physical exam was remarkable for bilateral lower extremity edema and dry mucous membranes.Labs revealed an elevated CRP (14) and normal ESR. Lipase and fecal elastase levels were normal, making worsening pancreatic insufficiency less likely. TSH was elevated, indicating true underactive thyroid disease, so her levothyroxine dose was increased. However, this was not believed to be the cause of her GI symptoms. CT abdomen/pelvis revealed a cystic lesion in the uncinate process, concerning for an intraductal papillary mucinous neoplasm (IPMN), which was later confirmed on MRCP, but also did not fully explain her symptoms. EGD showed scalloped mucosa in the duodenum concerning for celiac disease, as well as duodenitis, gastritis, and a small hiatal hernia. However, the patient’s tissue transglutaminase IgA antibodies were within normal limits. Upper GI tract biopsies were taken. Her colonoscopy was unremarkable, but biopsies were taken to rule out microscopic colitis. The patient was empirically started on a gluten-free diet given high concern for celiac disease, with no symptom resolution. Ultimately, the duodenal biopsy showed features suggestive of medication-induced enteropathy, specifically consistent with Olmesartan-associated changes. She had no villous atrophy, ruling out celiac disease. The patient was started on IV methylprednisolone with prompt symptom resolution and discharged on an extended budesonide course. Given the patient’s severe malnutrition, TPN was initiated. The patient’s lower extremity edema resolved after stopping amlodipine. A follow-up EGD four months later showed resolution of mucosal changes.
Discussion: Olmesartan has been implicated in a sprue-like enteropathy that may present months to years after initiation of therapy. Symptoms resolve after discontinuation of the drug and/or steroid therapy. Prompt recognition of this condition can prevent unnecessary interventions. Awareness of OIE is crucial when treating an elderly population, given these patients’ high medication burden and overlapping comorbidities.
Conclusions: OIE is a rare but increasingly recognized cause of severe chronic diarrhea and weight loss, particularly in elderly patients. This condition can clinically and histologically mimic celiac disease (increased intraepithelial lymphocytes, villous blunting), often delaying diagnosis. However, OIE lacks positive tissue transglutaminase IgA antibodies.