A 28-year-old woman from northern India with iron deficiency anemia undergoes investigation for the underlying cause. She denies menorrhagia and has no GI symptoms. Serum ferritin is low, TIBC is elevated, and fecal occult blood test is negative. Which is the most common cause of iron deficiency anemia in this clinical scenario?

Explanation

## Most Common Cause When Bleeding Is Excluded **Key Point:** When menorrhagia and GI bleeding are ruled out, dietary iron insufficiency becomes the most common cause of iron deficiency anemia, especially in resource-limited settings and developing countries like India. **High-Yield:** In this clinical scenario: 1. **Negative fecal occult blood** → rules out GI bleeding 2. **No menorrhagia history** → rules out excessive menstrual loss 3. **No GI symptoms** → malabsorption less likely 4. **Remaining mechanism** → inadequate dietary iron intake ### Causes of Iron Deficiency Anemia: Epidemiology by Setting | Cause | Developed Countries | Developing Countries (India) | Mechanism | | --- | --- | --- | --- | | **GI bleeding** | 40–50% | 20–30% | Occult/overt loss | | **Menorrhagia** | 30–40% | 20–30% | Menstrual loss | | **Dietary insufficiency** | 10–20% | 30–40% | Low intake/bioavailability | | **Malabsorption** | 5–10% | 5–10% | Reduced absorption | | **Hookworm/parasites** | <2% | 10–20% | Chronic blood loss + malabsorption | **Clinical Pearl:** In India, dietary iron deficiency is particularly common due to: - Predominantly vegetarian diets (lower bioavailability of non-heme iron) - Low consumption of vitamin C (enhances iron absorption) - High phytate/tannin content in staple foods (inhibit iron absorption) - Socioeconomic factors limiting access to iron-rich foods **Mnemonic:** **DIET** for iron insufficiency — **D**ietary intake low, **I**nadequate bioavailability, **E**ating patterns (vegetarian), **T**race element deficiency. ### Why Other Options Are Less Likely Here ```mermaid flowchart TD A[Iron Deficiency Anemia] --> B[Bleeding excluded] B --> C{GI symptoms present?} C -->|No| D[Malabsorption unlikely] C -->|Yes| E[Consider celiac, hookworm] D --> F{Dietary history?} F -->|Inadequate intake| G[Dietary insufficiency - MOST COMMON] F -->|Adequate intake| H[Malabsorption despite no symptoms] ``` **Warning:** Do not assume dietary insufficiency without taking a detailed dietary history. Some patients may have subclinical malabsorption (e.g., celiac disease) without overt GI symptoms. However, given negative FOB and no GI symptoms, dietary insufficiency is most likely.