Differential Diagnosis for 20-month-old with Diarrhea

• Single most likely diagnosis
  • Overuse or side effect of MiraLAX: The child's recent dose of MiraLAX, a laxative used to treat constipation, is the most likely cause of the diarrhea, given the temporal relationship between the administration of the medication and the onset of symptoms.
• Other Likely diagnoses
  • Viral gastroenteritis: Although the child denies fevers, vomiting, and URI symptoms, viral gastroenteritis can still be a cause of diarrhea, especially in a child who is otherwise healthy and eating/drinking fine.
  • Toddler's diarrhea: This is a common condition in toddlers characterized by chronic, non-bloody diarrhea, often related to dietary factors or gut motility issues.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Intussusception: Although less likely, intussusception is a serious condition where a part of the intestine telescopes into another, which can cause diarrhea, and if not diagnosed promptly, can lead to intestinal ischemia and necrosis.
  • Inflammatory bowel disease (IBD): Early onset IBD can present with chronic diarrhea, and although rare in this age group, it's crucial to consider to avoid delayed diagnosis and potential complications.
• Rare diagnoses
  • Celiac disease: An autoimmune reaction to gluten that can cause diarrhea, but it's less common in this age group and typically presents with other symptoms like failure to thrive or abdominal distension.
  • Giardiasis: A parasitic infection that can cause diarrhea, but it's less likely given the lack of exposure history (e.g., travel, daycare attendance) and absence of other symptoms like weight loss or abdominal pain.