Management of Left-Sided Pain with Iron Deficiency
This patient requires gastrointestinal investigation to identify the source of iron deficiency, despite having normal hemoglobin levels, because the ferritin of 19 ng/mL confirms absolute iron deficiency that demands evaluation for occult GI bleeding or malabsorption. 1
Critical Laboratory Interpretation
Your patient presents with a paradoxical picture:
- Iron deficiency is confirmed (ferritin 19 ng/mL, TSAT 20%) 1, 2
- No anemia present (hemoglobin 14.5 g/dL, hematocrit 44.5% are normal) 2
- Normal inflammatory markers (ESR 2, CRP 0.2) rule out anemia of chronic disease 1
- Left-sided pain raises concern for colonic pathology 1
This represents iron deficiency without anemia, which affects approximately 38% of adults and precedes the development of iron-deficiency anemia. 2
Immediate Diagnostic Workup Required
Mandatory Investigations
All patients with confirmed iron deficiency require bidirectional endoscopy (upper and lower GI evaluation) unless there is a clear non-GI explanation. 1, 3
Upper endoscopy (EGD) with duodenal biopsies to evaluate for:
Colonoscopy (preferred over CT colonography) to evaluate for:
Celiac serology (tissue transglutaminase IgA with total IgA level) should be obtained before endoscopy 1, 3
Important Caveats
- Do not attribute iron deficiency to diet alone without investigation - even with normal hemoglobin, the ferritin of 19 indicates depleted iron stores requiring explanation 1
- Faecal occult blood testing is not useful - it is insensitive and non-specific and should not be performed 1
- The normal inflammatory markers make inflammatory bowel disease less likely but do not exclude it 1
Iron Replacement Strategy
All patients with confirmed iron deficiency should receive iron supplementation to correct deficiency and replenish stores, regardless of hemoglobin level. 1
First-Line Oral Iron Therapy
- Ferrous sulfate 200 mg three times daily (or 325 mg daily) is the standard initial treatment 1, 2
- Alternative: Ferrous sulfate 325 mg on alternate days improves absorption and reduces side effects 2, 4
- Continue for 3 months after correction to replenish iron stores 1
- Ascorbic acid enhances absorption and should be considered if response is poor 1
When to Use Intravenous Iron
Intravenous iron is indicated if: 2, 4
- Oral iron intolerance (occurs in ~50% of patients) 4
- Malabsorption is identified (celiac disease, post-bariatric surgery) 1, 2
- Ongoing blood loss is documented 2
- Inadequate response to oral therapy after 2-4 weeks 4
Follow-Up Protocol
Monitor hemoglobin concentration every 3 months for one year, then annually. 1
- Expected response: Hemoglobin should rise by 2 g/dL after 3-4 weeks of oral iron 1
- Failure to respond indicates: poor compliance, continued blood loss, malabsorption, or misdiagnosis 1
- Further investigation is mandatory if hemoglobin and iron stores cannot be maintained with supplementation 1
Addressing the Left-Sided Pain
The left-sided pain in conjunction with iron deficiency raises specific concerns:
- Colorectal pathology must be excluded - left-sided colonic lesions (cancer, polyps, colitis) commonly present with iron deficiency 1
- Colonoscopy is non-negotiable in this clinical scenario, even with normal hemoglobin 1, 3
- The combination of symptoms and laboratory findings suggests occult GI bleeding until proven otherwise 1, 2
Red Flags Requiring Urgent Evaluation
Your patient should be evaluated urgently (within 2 weeks) because: 1
- Iron deficiency with localized GI symptoms suggests structural pathology
- Lower hemoglobin levels correlate with higher risk of serious disease, but even normal hemoglobin with iron deficiency warrants investigation 1
- Dual pathology (upper and lower GI lesions) occurs in 1-10% of cases 1
Do not delay investigation while treating with iron supplementation - the underlying cause must be identified to prevent progression of potentially serious disease. 1, 3