Most Likely Diagnosis: Crohn's Disease
Based on the constellation of chronic weight loss, fever, arthralgias, anemia, hypoalbuminemia, elevated CRP, and electrolyte abnormalities in a patient with a soft, non-tender abdomen and no organomegaly, Crohn's disease is the most likely diagnosis.
Clinical Reasoning
Key Diagnostic Features Supporting Crohn's Disease
The patient presents with the classic triad of abdominal pain, diarrhea (implied by 3-month weight loss), and weight loss, which are the hallmark symptoms of Crohn's disease 1, 2, 3. The 3-month duration of symptoms aligns with the chronic nature of inflammatory bowel disease, as symptoms persisting beyond 6 weeks typically distinguish IBD from infectious causes 4.
Systemic manifestations strongly favor Crohn's disease over other diagnoses:
- Fever (38.6°C) is more characteristic of Crohn's disease than ulcerative colitis 1, 2
- Arthralgias represent extraintestinal manifestations commonly seen in Crohn's disease 3
- Malaise and ill appearance reflect the systemic inflammatory burden 1
Laboratory Findings Consistent with Active Crohn's Disease
The biochemical profile demonstrates multiple abnormalities typical of active inflammatory bowel disease:
- Elevated CRP (1.1 mg/dL, normal 0-0.5) reflects active intestinal inflammation and correlates with disease activity 1, 3
- Anemia (Hb 82 g/L, normal 112-165) results from chronic inflammation, malabsorption, and potential occult bleeding 4, 3
- Hypoalbuminemia (32 g/L, normal 36-52) indicates both chronic inflammation and protein-losing enteropathy, which can be a severe complication of Crohn's disease 1, 5
- Hyponatremia (132 mmol/L) and hypokalemia (3.2 mmol/L) suggest chronic diarrhea with electrolyte losses 3
Why Not the Other Diagnoses?
Celiac disease (Option A) is less likely because:
- Celiac disease typically does not present with fever 3
- Arthralgias are uncommon in celiac disease
- The degree of systemic inflammation (elevated CRP) is atypical for celiac disease
- Celiac disease rarely causes this degree of hypoalbuminemia without severe malnutrition
Ulcerative colitis (Option C) is less likely because:
- Fever is less common in UC than in Crohn's disease 1, 2
- The absence of bloody diarrhea (not mentioned in the presentation) makes UC less probable, as bloody diarrhea is the cardinal symptom of UC 4
- Systemic symptoms and extraintestinal manifestations are more prominent in Crohn's disease 4, 2
Chronic dysentery (Option D) is unlikely because:
- The 3-month duration without mention of infectious exposure or travel history makes chronic infection less probable 4
- Chronic dysentery would typically show more acute abdominal findings on examination
- The constellation of extraintestinal manifestations (arthralgias) and chronic inflammatory markers favor IBD over infection
Critical Diagnostic Considerations
Important Caveat: Rule Out Abdominal Tuberculosis
A crucial pitfall to avoid is missing abdominal tuberculosis, which can present identically to Crohn's disease with fever, weight loss, abdominal pain, anemia, hypoalbuminemia, and elevated inflammatory markers 6, 2. The Centers for Disease Control and Prevention warn that treating presumed Crohn's disease with immunosuppression when the patient actually has tuberculosis can lead to fulminant TB progression and death 6.
Key features that should prompt consideration of abdominal TB:
- Fever with night sweats (present in 70-84% of TB cases) 6
- The ileocecal region is involved in 50-90% of gastrointestinal TB cases, identical to Crohn's disease 6, 2
- Up to 85% of abdominal TB patients have no pulmonary involvement, so absence of lung disease does not exclude TB 6
Next Steps in Diagnosis
According to ECCO-ESGAR guidelines, no single reference standard exists for diagnosing Crohn's disease; diagnosis requires a combination of clinical, biochemical, endoscopic, imaging, and histological investigations 4.
Mandatory initial investigations:
- Ileocolonoscopy with biopsies from inflamed and uninflamed segments to establish diagnosis 4
- Stool studies to exclude infectious causes, including C. difficile toxin and, if epidemiologically appropriate, tuberculosis culture 4
- Cross-sectional imaging (CT or MR enterography) to assess disease extent and detect complications 4
- Tuberculin skin test or interferon-gamma release assay if any risk factors for TB exist 6, 2
The most useful endoscopic features of Crohn's disease include discontinuous lesions, strictures, fistulae, and perianal involvement, though these findings are not specific 4.