A 35-year-old woman from rural India presents with fatigue and dyspnea on exertion. Laboratory investigations reveal microcytic hypochromic anemia with low serum ferritin and elevated TIBC. What is the most common cause of iron deficiency anemia in this patient?

Explanation

## Most Common Cause of Iron Deficiency Anemia in Women **Key Point:** In premenopausal women in India, menorrhagia (heavy menstrual bleeding) is the single most common cause of iron deficiency anemia, accounting for approximately 50–60% of cases in this demographic. **High-Yield:** The pathophysiology involves: 1. Excessive menstrual blood loss (>80 mL per cycle) 2. Chronic iron depletion exceeding dietary iron absorption 3. Negative iron balance leading to depleted iron stores (low ferritin) 4. Subsequent microcytic hypochromic anemia ### Why Menorrhagia Dominates in Women | Feature | Menorrhagia | GI Bleeding | Malabsorption | Hemolysis | | --- | --- | --- | --- | --- | | **Prevalence in premenopausal women** | 50–60% | 10–15% | <5% | <2% | | **Mechanism** | Excessive menstrual loss | Occult or overt GI loss | Reduced iron uptake | RBC destruction | | **Ferritin level** | Low | Low | Low | Normal/High | | **TIBC** | Elevated | Elevated | Elevated | Normal | | **Peripheral smear** | Microcytic hypochromic | Microcytic hypochromic | Microcytic hypochromic | Spherocytes, polychromasia | **Clinical Pearl:** Always ask about menstrual history in women with iron deficiency anemia. Menorrhagia is often underreported and may coexist with other causes (e.g., a woman with menorrhagia AND a peptic ulcer). **Mnemonic:** **IRON** causes in women — **I**ncreased menstrual loss, **R**educed absorption, **O**ccult GI bleeding, **N**eed for iron supplementation. Menorrhagia is the leading I. ### Laboratory Findings in This Case - **Low serum ferritin** → depleted iron stores - **Elevated TIBC** → increased iron-binding capacity (reflects increased transferrin production in response to iron deficiency) - **Microcytic hypochromic RBCs** → small, pale cells due to reduced hemoglobin synthesis **Warning:** Do not confuse elevated TIBC with hemolysis. In hemolysis, ferritin is normal or elevated (due to iron release from lysed RBCs), and TIBC is normal.