Anemia is defined as a hemoglobin level 2 standard deviations below normal for age and sex. Iron deficiency anemia is anemia resulting from inadequate iron supplementation or excessive blood loss.

Anemia Iron deficiency

• Dietary iron deficiency occurs often in infants as a result of unsupplemented milk diets. It is also commonly seen in women during their reproductive yr, as a result of heavy menstrual periods, and during pregnancy (increased demand).
• Iron deficiency is the most common nutritional deficiency worldwide.
• The prevalence of iron deficiency is greatest among toddlers ages 1 to 2 yr (7%) from inadequate intake and female individuals ages 12 to 49 yr (9%-16%) from menstrual losses.
• The prevalence of iron deficiency is 2% in adult men, 9% to 12% in non-Hispanic White women, and 20% in Black and Mexican American women.
• GI cancer is diagnosed in 10% of elderly patients with iron deficiency anemia.

• Most patients have normal examination results.
• Skin pallor and conjunctival pallor may be present.
• Signs and symptoms specific for iron deficiency are koilonychias, pica, pagophagia, blue sclera, glossitis, and angular stomatitis (Fig. E1).
• Patients with severe anemia can have palpitations, headache, weakness, dizziness, and easy fatigability.

• Blood loss from GI or menstrual bleeding (genitourinary blood loss less often the cause)
• Dietary iron deficiency (rare in adults)
• Poor iron absorption in patients with gastric or small-bowel surgery
• Repeated phlebotomy
• Increased requirements (e.g., during pregnancy)
• Other: Traumatic hemolysis (abnormally functioning cardiac valves), idiopathic pulmonary hemosiderosis (iron sequestration in pulmonary macrophages), paroxysmal nocturnal hemoglobinuria (intravascular hemolysis)
• The most common cause worldwide is hookworm infection

• Anemia of chronic disease
• Sideroblastic anemia
• Thalassemia trait
• Lead poisoning

Diagnostic workup consists primarily of laboratory evaluation. Table 1 describes laboratory studies differentiating the most common microcytic anemias. Most patients with iron deficiency anemia are asymptomatic in the early stages. With progressive anemia, the major symptoms are fatigue, dizziness, exertional dyspnea, pagophagia (ice eating), and pica. Patient history may also suggest GI blood loss (melena, hematochezia, hemoptysis).

• Laboratory results vary with the stage of deficiency.
• Absent iron marrow stores and decreased serum ferritin are the initial abnormalities.
• Decreased serum iron and increased total iron-binding capacity (TIBC) are the next abnormalities.
• Hypochromic microcytic anemia is present with significant iron deficiency.
• Peripheral smear in patients with iron deficiency generally reveals microcytic hypochromic red blood cells (Fig. E2) with a wide area of central pallor, anisocytosis, and poikilocytosis when severe.
• Laboratory abnormalities consistent with iron deficiency are low serum ferritin level, increased RBC distribution width with values generally >15, low mean corpuscular volume, low mean corpuscular hemoglobin, increased TIBC, and low serum iron.
• In patients diagnosed with iron deficiency anemia, a GI workup including an upper endoscopy and colonoscopy is recommended to look for source of iron loss.

Patients should be instructed to consume foods that contain large amounts of iron, such as liver, red meat, and legumes.

• Iron supplementation will result in reticulocytosis and will generally increase hemoglobin levels by 0.5 to 1 g per wk.
• Treatment consists of ferrous sulfate 325 mg PO daily for 3 to 6 mo. Doses higher than 325 mg/day are poorly tolerated. Calcium supplements can decrease iron absorption; therefore these medications should be staggered. Supplemental vitamin C can increase oral absorption.
• Parenteral iron therapy is reserved for patients with poor tolerance, noncompliance with oral preparations, or malabsorption. Indications for intravenous iron therapy are summarized in Table 2.
• Transfusion of packed RBCs is indicated in patients with severe symptomatic anemia.

Patients should be instructed to continue their iron supplements for at least 6 mo or longer to correct depleted body iron stores.

• Most patients respond rapidly to iron supplementation with improvement in CBC and general well-being (Table 3). GI side effects from oral iron therapy are common and may require decreased dosage to once every other day or to change to parenteral iron.
• A differential diagnosis of microcytic anemia that fails to respond to oral iron is described in Table 4.

GI referral for evaluation of GI malignancy is recommended in all patients with iron deficiency and suspected GI blood loss.

• Iron deficiency may impair aerobic performance and worsen symptoms in patients with heart failure. Treatment with intravenous iron in patients with chronic heart failure and iron deficiency has been shown to improve symptoms, quality of life, and functional capacity.
• If the diagnosis of iron deficiency anemia is made, locating the suspected site of iron loss is mandatory.

Algorithm for Diagnosis of Anemias (Algorithm in Section III)

Anemia (Patient Information)