Which of the following is the most common cause of iron deficiency anemia worldwide?

Explanation

## Etiology of Iron Deficiency Anemia **Key Point:** While chronic GI blood loss is the most common cause in developed countries, nutritional iron deficiency (inadequate dietary intake) remains the leading cause globally, particularly in developing nations and resource-limited settings. ### Geographic and Demographic Variation | Cause | Prevalence | Geography | |-------|-----------|----------| | Nutritional deficiency | Most common worldwide | Developing countries, low SES | | Chronic GI blood loss | Most common in developed nations | USA, Europe, Australia | | Menorrhagia | Common in reproductive-age women | All regions | | Malabsorption | Less common | Post-surgical, celiac disease | **High-Yield:** In NEET PG exams, when asked about the "most common cause worldwide," the answer is nutritional deficiency. When asked about "most common cause in India" or "in a hospital setting," GI blood loss becomes more relevant. **Clinical Pearl:** The distinction matters: nutritional IDA typically affects children and women in developing countries; GI blood loss IDA affects older adults in developed countries. ### Why Other Options Are Wrong - **Hemolysis:** Causes anemia but does NOT deplete iron stores; RBC life span is shortened, not iron absorption impaired. - **Bone marrow failure:** Results in pancytopenia or selective erythroid hypoplasia, not iron deficiency.