anemia%20-%20iron-deficiency
ANEMIA - IRON-DEFICIENCY
Anemia is a condition wherein the blood has low levels of red blood cells (RBC), hemoglobin (oxygen-carrying pigment in whole blood) and/or hematocrit (intact RBC in blood) making it insufficient to address the physiologic needs of the body.
Iron-deficiency anemia is the anemia that resulted from inadequate iron supplementation or excessive blood loss.
It is the most common nutritional disorder worldwide and accounts for more than half of anemia cases.
It is prevalent among preschool children and pregnant women.

Principles of Therapy

  • Iron-deficiency anemia caused by an underlying condition should be treated or referred to a subspecialist for further workup and definite treatment
  • Patients with iron-deficiency anemia have good response from iron therapy

Pharmacotherapy

Iron Therapy (Oral)

  • Oral administration is the preferred route of iron therapy
  • Oral ferrous iron is readily absorbed due to higher solubility while ferric iron has a longer period of active absorption but both have been effective in correction of iron-deficiency anemia
  • Carbonyl iron consists of microparticles of elemental iron, thus it is not an iron salt
    • It is also used for iron-deficiency anemia
  • The dosage of elemental iron required to treat iron-deficiency anemia in adults is 100-200 mg/day for 3 months
  • Recommended doses for children are 3-6 mg/kg/day of elemental iron in liquid preparation for 3-4 months
  • GI adverse effects such as epigastric discomfort, nausea, diarrhea, metallic taste, thick, green stool and mild to severe constipation (usually in pregnant women) may cause non-compliance to therapy
    • These GI effects are usually seen in ferrous iron forms and can be minimized by taking the oral iron supplement after meals although it may cause decreased absorption
    • Ferric iron and slow-release ferrous salt have reduced GI disturbances thus have better tolerance rate
  • Iron absorption is enhanced in a mildly acidic medium, thus addition of ascorbic acid (either by tablet or half-glass of orange juice) has been suggested
    • Studies have shown that ascorbic acid can overcome the negative effect of iron absorption of all inhibitors, including phytate, polyphenols and the calcium and proteins in milk products, and it will increase the absorption of both native and fortified iron
  • Intake of proton pump inhibitors and those that induce gastric acid hyposecretion can reduce iron absorption
  • Once adequate response to treatment (increase in hemoglobin of 1g/dL) after a month has been established, therapy should be continued for 3-6 months for iron stores to become replenished 
  • Switch to a low-dose oral iron for maintenance once iron-deficiency anemia has resolved 
  • Oral therapy combinations of iron, folic acid, vitamin B12, and vitamin C are administered easier in women than the single component oral iron preparations

Iron Therapy (Parenteral)

  • Indicated in patients who cannot tolerate or absorb oral preparations, those with inadequate response to appropriate oral therapy for 3 months, who did not tolerate trial therapy with 2 different oral iron agents, with hemoglobin levels continuing to fall, worsening symptoms of inflammatory bowel disease, unresolved bleeding, and renal failure-induced anemia treated with erythropoietin
  • IV iron therapy is also indicated if condition requires a rapid increase in hemoglobin level, or if the amount of iron to be replenished exceeds the capacity of the GI tract to absorb oral iron preparations
  • IV iron therapy is preferred in hemodialysis patients
  • Iron dextran, Iron sorbitol, Iron sucrose, Ferric carboxymaltose and Sodium ferric gluconate are the most common parenteral forms of iron therapy
  • IV iron therapy has risk of serious allergic reactions
    • Studies have shown that there are higher risks with high-molecular-weight iron dextran than with low-molecular-weight iron dextran and non-dextran forms (eg Iron sucrose, Sodium ferric gluconate)
    • Underuse of IV iron may have stemmed in part from concerns about the risk of serious allergic reactions
  • IM injection of iron is discouraged due to associated pain, permanent skin staining, variable absorption and not safer than IV infusion
  • A “total-dose” infusion (where iron stores can be repleted in a single treatment episode) can also be given

Non-Pharmacological Therapy

Blood Transfusion

  • Indicated in patients who are unstable hemodynamically due to active bleeding, pregnant women with hemoglobin levels <6 g/dL, and/or show evidence of end-organ ischemia
  • It is essential to assess the patient’s clinical condition and symptoms in deciding whether blood transfusion is needed
  • Transfuse one unit a time of packed RBC if transfusion is indicated
    • Clinical situation should be reassessed to guide further treatment
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