Differential Diagnosis

Based on the provided information, the following differential diagnoses are considered:

• Single most likely diagnosis
  • Irritable Bowel Syndrome (IBS): The patient's symptoms of abdominal issues, slightly elevated lactoferrin, and acidic poop at 5.5, despite a clear GI workup, may suggest IBS. The previous E. coli infection and colonoscopy prep could have triggered or exacerbated IBS symptoms.
• Other Likely diagnoses
  • Post-Infectious IBS (PI-IBS): Given the patient's history of E. coli infection, it is possible that they developed PI-IBS, which can cause persistent gastrointestinal symptoms after an infectious episode.
  • Small Intestine Bacterial Overgrowth (SIBO): The patient's symptoms, such as acidic poop, could be indicative of SIBO, which may have been triggered by the previous antibiotic treatments or colonoscopy prep.
  • Inflammatory Bowel Disease (IBD) - mild: Although the GI workup was clear, it is possible that the patient has a mild form of IBD, such as ulcerative colitis or Crohn's disease, which may not have been detected.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Colon Cancer: Although the colonoscopy was likely clear, it is essential to consider the possibility of colon cancer, especially if the patient has a family history or other risk factors.
  • Lymphoma: Low sigA levels can be associated with lymphoma, and it is crucial to rule out this possibility, especially given the patient's history of antibiotic treatments and colonoscopy prep.
• Rare diagnoses
  • Whipple's Disease: This rare bacterial infection can cause gastrointestinal symptoms, including diarrhea and abdominal pain, and may be considered if other diagnoses are ruled out.
  • Autoimmune Enteropathy: This rare condition is characterized by autoimmune-mediated damage to the small intestine and can cause symptoms similar to those experienced by the patient.