Iron deficiency anemia is in which iron loss exceeds intake. May occur as a result of ↑demand (growth phase, pregnancy, erythropoietin [EPO] therapy) or ↓iron (chronic menorrhagia, GI bleeding, malnutrition/absorption disorders like celiac). Toddlers, adolescent girls, and women of childbearing age are most commonly affected.
History/PE – Iron deficiency anemia
- Symptoms: Fatigue, dyspnea, tachycardia, angina, syncope, and pica.
- If the anemia develops slowly, patients are generally asymptomatic.
- Physical findings: Glossitis, conjunctival pallor, cheilosis, and koilonychia (“spoon nails,” see Figure 1).
Diagnosis – Iron deficiency anemia
Microcytic anemias, or microcytosis, have a low MCV (< 80 fL) and generally have a low reticulocyte count.
- Best initial test: CBC (↓ MCV, ↓ MCH, ↓ MCHC) with iron studies (see Figure 1). No single value is diagnostic, but the constellation of the following points to the correct diagnosis:
- ↓ Ferritin (↓ iron stores).
- ↑ RBC distribution width (RDW), reflecting high RBC size variation caused by poor erythropoiesis.
- ↑ Total iron-binding capacity (TIBC); ↓ iron means many empty receptors, so binding capacity is ↑.
- ↓ Serum iron.
- Most accurate test: Bone marrow biopsy is seldom performed.
- Peripheral blood smear shows microcytic, hypochromic RBCs (see Figure 3) with anisocytosis, poikilocytosis, and a low reticulocyte count.
Iron deficiency anemia in an elderly patient may be caused by colorectal cancer until proven otherwise and must therefore be evaluated to rule out malignancy.
Treatment – Iron Deficiency Anemia
- Replace iron orally until normal and for at least 4–6 months to replenish stores. Oral iron sulfate may lead to nausea, constipation, diarrhea, abdominal pain, and black stools. Antacids may interfere with iron absorption.
- If the oral route is insufficient, use intramuscular iron.
- IV iron circumvents gastrointestinal absorption and is therefore only considered as a preferred agent if the oral route is ineffective, such as with gluten sensitivity, inflammatory bowel disease, gastrointestinal malabsorption, post–gastric bypass surgery, hyperemesis gravidarum, and a history of oral iron intolerance.
- IV iron is superior to oral iron in achieving a sustained Hb response, reducing the need for packed RBC transfusions, and improving the quality of life for patients with chronic heart failure, inflammatory bowel disease, chronic kidney disease and hemodialysis, and cancer-related anemia.
- IV iron dextran is associated with a small risk for serious side effects, including anaphylaxis. Iron sucrose may be associated with a lower risk for allergy.