Differential Diagnosis for Abdominal Pain with Diarrhea
The patient presents with abdominal pain, diarrhea for two weeks, and a CT scan that is negative. Laboratory results show elevated platelets (385) but are otherwise normal. Here's a differential diagnosis organized into categories:
Single Most Likely Diagnosis
- Irritable Bowel Syndrome (IBS): Given the chronic nature of the diarrhea and abdominal pain without other alarming signs, IBS is a strong consideration. The normal laboratory results and negative CT scan also support this diagnosis, as IBS is a diagnosis of exclusion.
Other Likely Diagnoses
- Infectious Gastroenteritis: Although the diarrhea has been present for two weeks, which is longer than typical for viral gastroenteritis, some bacterial or parasitic infections can cause prolonged symptoms.
- Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease or ulcerative colitis could present with chronic diarrhea and abdominal pain. The elevated platelet count could be a marker of inflammation.
- Lactose Intolerance or Other Food Intolerances: These conditions can cause chronic gastrointestinal symptoms, including diarrhea and abdominal pain, without abnormal laboratory findings.
Do Not Miss Diagnoses
- Colon Cancer: Although less likely in younger patients, colon cancer can present with chronic diarrhea and abdominal pain. A negative CT scan does not rule out this diagnosis, especially if the tumor is small or in an early stage.
- Neuroendocrine Tumors: Certain tumors, like carcinoids, can cause chronic diarrhea and abdominal pain due to the secretion of various hormones.
- Ischemic Bowel Disease: This condition can present with abdominal pain and chronic diarrhea, especially in older patients or those with risk factors for vascular disease.
Rare Diagnoses
- Whipple's Disease: A rare, systemic bacterial infection that can cause chronic diarrhea, abdominal pain, and malabsorption.
- Tropical Sprue: A rare condition that causes chronic diarrhea and malabsorption, typically seen in individuals who have traveled to or lived in tropical areas.
- Eosinophilic Gastroenteritis: A rare condition characterized by eosinophilic infiltration of the gastrointestinal tract, leading to chronic gastrointestinal symptoms.
Each of these diagnoses should be considered in the context of the patient's full clinical picture, including history, physical examination, and response to initial treatments. Further diagnostic testing may be necessary to confirm the diagnosis.