A 32-year-old woman with menorrhagia presents with iron deficiency anemia (Hb 8.5 g/dL, serum ferritin 12 ng/mL, TIBC elevated). She has no gastrointestinal symptoms. What is the drug of choice for iron replacement?

Explanation

## Iron Replacement in Iron Deficiency Anemia ### First-Line Oral Iron Therapy **Key Point:** Ferrous sulfate 325 mg once daily is the gold standard first-line treatment for iron deficiency anemia in patients with intact gastrointestinal absorption. **High-Yield:** Ferrous salts (ferrous sulfate, ferrous fumarate, ferrous gluconate) are preferred over ferric salts because ferrous iron (Fe²⁺) is absorbed more efficiently in the duodenum and proximal jejunum than ferric iron (Fe³⁺). ### Dosing & Absorption | Parameter | Ferrous Sulfate | Ferrous Gluconate | Ferric Carboxymaltose | | --- | --- | --- | --- | | **Elemental iron per dose** | 65 mg (325 mg salt) | 36 mg (300 mg salt) | 750 mg (IV only) | | **Route** | Oral | Oral | IV | | **First-line status** | Yes | Alternative oral | Reserved for IV indication | | **Cost** | Low | Low | High | | **GI side effects** | Common | Less common | None (IV) | ### When to Use IV Iron **Clinical Pearl:** IV iron (ferric carboxymaltose, iron sucrose, iron dextran) is reserved for: - Intolerance to oral iron (severe GI upset, nausea) - Malabsorption syndromes (celiac disease, post-gastrectomy) - Chronic kidney disease on hemodialysis - Inability to meet iron needs orally (ongoing blood loss) - Pregnancy with severe anemia **Warning:** IM iron (iron dextran) is rarely used now due to risk of local reactions, staining, and superior efficacy of IV formulations. ### Expected Response 1. Reticulocytosis begins within 3–5 days 2. Hemoglobin rise: 1–2 g/dL per week 3. Ferritin normalization: 3–6 months 4. Total iron stores replenishment: 6–12 months **Mnemonic:** **FIGS** — Ferrous Iron is Gut-absorbed Superbly (compared to ferric).