Differential Diagnosis for Chronic Morning Diarrhea
Single Most Likely Diagnosis
- Irritable Bowel Syndrome (IBS): This condition is characterized by chronic abdominal pain, bloating, and alteration of bowel habits in the absence of any mechanical, inflammatory, or biochemical abnormalities. The patient's symptoms of chronic morning diarrhea, worsening with food intake, and fluctuating severity are consistent with IBS. The presence of depression and anxiety also supports this diagnosis, as there is a known association between IBS and psychiatric comorbidities.
Other Likely Diagnoses
- Bile Acid Diarrhea: Given the patient's history of cholecystectomy (gallbladder removal), bile acid diarrhea is a plausible diagnosis. The absence of a gallbladder can lead to an imbalance in bile acid production and absorption, causing chronic diarrhea.
- Gastroesophageal Reflux Disease (GERD): Although primarily associated with heartburn and regurgitation, some patients with GERD may experience diarrhea, possibly due to the gastrocolic reflex, which is stimulated by food intake.
- Inflammatory Bowel Disease (IBD): While the patient's normal blood investigations and ultrasounds make this less likely, IBD (including Crohn's disease and ulcerative colitis) can present with chronic diarrhea and should be considered, especially if there are any signs of inflammation or if the patient's symptoms worsen over time.
Do Not Miss Diagnoses
- Celiac Disease: An autoimmune disorder caused by a reaction to gluten, leading to small intestine damage and chronic diarrhea. It's crucial to rule out celiac disease due to its potential for long-term complications if left untreated.
- Thyroid Disorders: Both hyperthyroidism and hypothyroidism can cause gastrointestinal symptoms, including diarrhea. Given the patient's chronic symptoms, evaluating thyroid function is essential.
- Infections: Chronic infections such as giardiasis or other parasitic infections can cause persistent diarrhea and should be considered, especially with the patient's history of travel-related diarrhea.
Rare Diagnoses
- VIPoma: A rare endocrine tumor that produces vasoactive intestinal peptide (VIP), leading to a syndrome characterized by large-volume diarrhea, hypokalemia, and achlorhydria.
- Carcinoid Syndrome: Although rare, this condition, often associated with neuroendocrine tumors, can cause diarrhea among other symptoms like flushing and wheezing.
- Short Bowel Syndrome: This condition, resulting from a significant resection of the small intestine, can lead to chronic diarrhea due to the reduced absorptive surface area. However, given the patient's history, this seems less likely unless there were complications from the cholecystectomy that were not mentioned.