Differential Diagnosis
Given the patient's history and laboratory results, the following differential diagnoses are considered:
Single most likely diagnosis
- Active Crohn's disease: The elevated calprotectin level (52.6) is a strong indicator of intestinal inflammation, which is consistent with active Crohn's disease. The patient's previous diagnosis of Crohn's disease and the presence of absolute lymphocytes (3.2) also support this diagnosis. Although the colonoscopy 18 months ago was normal, Crohn's disease can be patchy and may not always be detected by endoscopy.
Other Likely diagnoses
- Irritable Bowel Syndrome (IBS): Although less likely given the elevated calprotectin, IBS can sometimes present with elevated inflammatory markers. However, the presence of absolute lymphocytes and the patient's history of Crohn's disease make this less likely.
- Infectious gastroenteritis: This could cause an elevation in calprotectin levels, but the patient's history and the absence of other symptoms (such as diarrhea, fever, or abdominal pain) make this less likely.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Colon cancer: Although the colonoscopy 18 months ago was normal, the possibility of a new or missed lesion cannot be entirely ruled out, especially in a patient with a history of Crohn's disease, which increases the risk of colon cancer.
- Lymphoma: Given the patient's history of Crohn's disease and the presence of absolute lymphocytes, there is a small but significant risk of lymphoma, which is a known complication of long-standing inflammatory bowel disease.
Rare diagnoses
- Microscopic colitis: This condition can cause chronic diarrhea and inflammation in the colon, but it is less likely given the patient's history and the presence of elevated calprotectin.
- Eosinophilic gastroenteritis: This is a rare condition characterized by eosinophilic infiltration of the gastrointestinal tract, but it is unlikely given the patient's presentation and laboratory results.