Anemia and Iron Deficiency Overview

Anemia

• Anemia is defined as a below-normal plasma hemoglobin concentration.
• Causes of anemia include nutritional deficiencies (iron, folic acid, vitamin B12), chronic blood loss, bone marrow abnormalities, increased hemolysis, infections, malignancy, chronic diseases (endocrine deficiencies, renal failure), and drug-induced toxic effects on blood cells, hemoglobin production, or erythropoietic organs.
• Genetic factors, excessive bleeding (menstrual bleeding, iron deficiency anemia, cancer causing anemia), and impaired metabolism of the spleen and anemia can also contribute to the cause of anemia.

Iron Deficiency Anemia

• Iron deficiency is a common cause of chronic anemia.
• Iron is crucial for the formation of hemoglobin.
• Iron forms the core of the heme group within hemoglobin.
• Globin chains combine with heme to form hemoglobin.
• Daily iron loss from the body is small, so dietary requirements are modest.

Causes of Iron Deficiency

• Diet: Insufficient intake, malnutrition, dietary factors (polyphenols, tannins).
• Absorption Issues: Gastritis, celiac disease, enteritis, surgical procedures, drugs, infections.
• Blood Loss: Gastrointestinal lesions, cancer, heavy menstrual bleeding, blood donations, hematuria, coagulopathy, inflammatory bowel disease (IBD).
• Inflammation: Increased levels of hepcidin.
• Increased Needs: Pregnancy, children, athletes, patients undergoing chemotherapy or EPO.
• Others: Hemolysis (destruction of red blood cells), various iron metabolism disorders.

Oral Iron Therapy

• Ferrous iron is absorbed more efficiently than ferric iron.
• Daily iron need is approximately 50-100 mg.
• About 25% of oral iron is absorbed, so 200-400 mg of elemental iron is often required daily for effective correction of iron deficiency.
• Oral iron therapy should be administered for 3-6 months to replenish iron stores and correct anemia.

Parenteral Iron Therapy

• Reserved for patients with intolerance or poor absorption of oral iron, or those with severe chronic anemia.
• Parenteral iron formulations include iron dextran, sodium ferric gluconate complex, and iron sucrose.

Iron Toxicity

• Primarily affects young children.
• Ingestion of even a small number of oral iron tablets can be fatal in children.
• Symptoms of acute iron toxicity can include GI irritation, shock, metabolic acidosis, and hepatic necrosis.
• Supportive treatment includes measures to manage gastrointestinal bleeding, metabolic acidosis, or shock.
• Whole bowel irrigation can be used to flush out unabsorbed pills.
• Hemodialysis is not effective for acute iron toxicity as iron has a large volume of distribution.
• Exchange transfusion or deferoxamine, an iron chelating drug, might be considered.

Folic Acid Deficiency

• Folic acid is vital for DNA synthesis and cell division.
• Significant daily requirement is 50 µg.
• A deficiency can cause megaloblastic anemia and neuropathies.
• Causes of deficiency include increased demand (pregnancy, lactation), poor absorption (intestinal diseases), alcoholism, and medications like methotrexate, pyrimethamine, and trimethoprim.
• High doses of folic acid (up to 5mg/day) may be required in certain cases.

Vitamin B12 Deficiency Anemia

• Vitamin B12 is crucial for neurological function, red blood cell production, and DNA synthesis.
• It is acquired from diet.
• B12 absorption occurs in the terminal ileum of the small intestine with the help of intrinsic factor.
• Deficiency can cause megaloblastic anemia and neurological abnormalities.
• Causes include low dietary intake or poor absorption (pernicious anemia or decreased intrinsic factor production).
• Oral or parenteral supplementation is required to treat deficiencies.

Sickle Cell Disease

• Agents used to treat sickle cell disease includes hydroxyurea which apparently increases fetal hemoglobin, which can diluted abnormal hemoglobin S (HbS).
• Additional agents can include pentoxifylline which improves erythrocyte flexibility and reduces blood viscosity.

Chronic Iron Toxicity

• Known as hemochromatosis.
• Treatment often involves intermittent phlebotomy.
• Deferasirox (an oral iron chelator) is a treatment option for iron overload.