Anemia Types and Iron Therapy

• Anemia occurs when hemoglobin (Hb) levels are below the reference range
• Low Hb is defined as <13 g/dL for men and <12 g/dL for women based on WHO criteria

Types of Anemias

• Types include iron deficiency, megaloblastic, hemolytic, and aplastic anemia
• Megaloblastic anemia is due to folic acid/vitamin B12 deficiency
• Hemolytic anemia can be congenital or acquired, such as from drug toxicity
• Aplastic anemia is a failure of bone marrow proliferation from neoplasms or drug toxicity

Iron Therapy

• Iron must be converted to the ferrous state for absorption, which occurs in the duodenum and proximal jejunum
• Factors increasing iron absorption include vitamin C, anemia, HCL, pregnancy, and infancy
• Factors decreasing iron absorption include concurrent administration of antacids, tetracyclines, tannic acid (strong tea), and desferrioxamine

Indications of Iron Therapy

• Used to treat iron deficiency anemia (hypochromic microcytic)
• Used during treatment of megaloblastic anemia and anemia of chronic renal failure, as iron stores are depleted due to increased RBC synthesis

Iron Preparations: Oral Iron Therapy

• Ferrous iron is the most efficiently absorbed form
• Ferrous sulfate, ferrous gluconate, and ferrous fumarate are effective and recommended for treatment
• Recommended daily dose for adults with iron deficiency is 150-200 mg/day of elemental iron such as 200mg ferrous sulfate, three times daily

Monitoring Iron Therapy

• Reticulocytosis begins in approximately 7 days, with hemoglobin rising about 2 g/dL over three weeks
• Hemoglobin levels should normalize in 1-3 months
• Treatment with oral iron should continue for 6 months after hemoglobin reaches normal levels to replenish iron stores

Side Effects of Iron Therapy

• 20-25% of patients on iron therapy experience GI side effects such as abdominal bloating, pain, nausea, vomiting, diarrhea/constipation
• Reducing elemental iron concentration per dose may help
• Dark stools can occur, potentially obscuring the diagnosis of gastrointestinal blood loss (melena)
• Parenteral iron therapy is considered when pateints are unable to tolerate oral iron

Parenteral Iron Therapy

• Parenteral iron therapy involves slow and occasional incomplete mobilization of iron from intramuscular sites
• Hemoglobin concentration increases only slightly faster than with oral iron
• Indications include iron deficiency with intolerance or inability to absorb oral iron
• Use for severe anemia or extensive chronic blood loss not corrected by oral iron

Iron Preparations: Parenteral

• Iron dextran complex is administered via IV injection
• Iron sucrose (Venofer®) IV is effective and has a lower anaphylaxis risk than iron dextran

Side Effects of Parenteral Iron Therapy

• Local pain and tissue staining can occur with I.M. injection, causing brown discoloration
• Headache, fever, joint pain, and muscle pain are possible
• Urticaria, bronchospasm, and rarely anaphylaxis can occur; a small test dose of iron dextran should be given 30-60 minutes prior

Iron Toxicity

• Fatal overdose is possible, mostly in children
• Deferroxamine used to treat because it is an iron-chelating agent

Vitamin B12 Therapy

• Parietal cells of gastric mucosa secrete intrinsic factor, essential for vitamin B12 absorption
• Absorption mainly occurs in the terminal ileum
• Use Hydroxocobalamin dose of 1000 µg (1 mg) IM daily for one week, then 1 mg weekly for four weeks
• If underlying disorder persists, as in pernicious anemia, administer 1 mg monthly for life

Indications for B12 Therapy

• Vitamin B12 deficiency is indicated, especially when caused by Pernicious anemia
• Also used for Malabsorption syndromes
• Used when Drugs cause malabsorption of vitamin B12, e.g. antiretroviral and metformin
• Can be used for Peripheral neuropathy especially in diabetes mellitus
• Hydroxycobalamin can be used in cyanide poisoning, which it combines to form cyanocobalamin, cleared renally

Folic Acid (Vitamin B9)

• Dose: 1 to 5 mg/day PO for one to four months, or until complete hematologic recovery

Indications for Folic Acid

• Megaloblastic anemia
• Malabsorption syndrome
• Pregnancy: folate requirement increases from 400µg to 800µg/day
• Prevention of fetal neural tube defects (spina bifida)
• Treat drug-induced folate deficiency, e.g., phenytoin and trimethoprim

Erythropoietin

• Erythropoietin manages anemia of chronic renal failure
• It is also used in severe anemia of cancer
• It is administered intramuscularly (IM) or subcutaneously (SC)

Adverse Effects of Erythropoietin

• It can bring on iron deficiency in patients with chronic renal failure
• It increases blood viscosity, increasing risk of VTE (Venous thromboembolism)
• Hypertension due to rapid increase in RBCs and blood viscosity
• Red cell aplasia can occur because of antibodies directed against the EPO molecule, necessitating stopping treatment, but is rare