Iron Metabolism and Deficiency Anemia
Importance of Iron
- Essential for metabolic processes:
- Oxygen transport
- DNA synthesis
- Electron transport
- Iron deficiency:
- Decreased total body iron content
- Leads to iron deficiency anemia when red blood cell production is diminished
Iron Metabolism
- Average 70 kg person:
- Total body iron content: ~4 grams
- Hemoglobin: ~2500 mg
- Circulating in plasma: ~4 mg
- Stored as ferritin: ~1000 mg
- Myoglobin and enzymes: ~300 mg
- Daily iron cycle:
- Intestinal absorption: 1-2 mg
- Loss from body: 1-2 mg
- Red blood cell production: ~20 mg (replenished from recycled iron)
Iron Absorption
- Dietary Iron Forms:
- Heme Iron: from animal food, better absorbed
- Non-Heme Iron: from plant food, poorly absorbed, mostly ferric ion
- Absorption Process:
- Heme iron enters cell
- Iron converted to ferric by heme oxidase
- Non-heme iron converted to ferrous by duodenal cytochrome B
- Ferrous absorbed via DMT1
- Ferrous leaves cell via ferroportin
- Converted to ferric by hephastin
- Binds to transferrin in plasma
- Excess stored as ferritin
- Hepcidin: regulates iron metabolism by inhibiting ferroportin
Causes of Iron Deficiency Anemia
- Dietary Factors:
- Heme iron well absorbed; non-heme iron absorption impaired by dietary constituents
- Less meat intake can lead to deficiency
- Hemorrhage:
- Blood loss depletes iron stores
- Chronic bleeding from pregnancy, tumors, NSAIDs, etc.
- Malabsorption:
- Conditions like echlorhydria, celiac disease, gastric surgery
- Rare Causes:
- Iron refractory iron deficiency (genetic)
- Hemoglobinuria (conditions affecting kidneys)
- Pulmonary hemocytosis (intraalveolar bleeding)
Clinical Presentation
- Gradual development, often asymptomatic at first
- Symptoms: fatigue, pagophagia, leg cramps
- Physical signs: pallor, koilonychia, angular stomatitis
- Complications: hypoxemia, gastric atrophy, impaired immunity
Diagnosis
- Laboratory Tests:
- Complete blood count (microcytic hypochromic anemia)
- Peripheral smear
- Serum iron, TIBC, ferritin levels
- Additional tests for etiology: hemoglobinuria, stool testing
Treatment
- Oral iron therapy
- Correct underlying causes
- Avoid iron in conditions like thalassemia
- Parenteral iron for specific cases, risk of anaphylaxis
- Androgen replacement in postmenopausal women if needed
Feel free to ask questions or discuss further in the comments section.