Iron Deficiency Anemia

Iron Deficiency Anemia is a topic covered in the 5-Minute Pediatric Consult.

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Basics

Description

A reduction in hemoglobin production due to an insufficient supply of iron that results in a microcytic, hypochromic anemia

Epidemiology

  • Iron deficiency is the most common nutritional deficiency of children.
  • Leading cause of anemia among infants and children in the United States
  • Most commonly seen in children ages 9 months to 3 years and in teenage girls

Prevalence

  • Prevalence is variable depending on socioeconomic status, availability of iron-fortified formulas, and prevalence and duration of breastfeeding.
  • Prevalence of iron deficiency anemia in United States is generally between 1% and 5% of children.

Risk Factors

  • Low socioeconomic status
  • Certain ethnic groups (e.g., Southeast Asian) may be at increased risk due to dietary practices.
  • History of prematurity

General Prevention

  • Maintain breastfeeding for the first 5 to 6 months of life if possible.
    • Breast milk has lower iron concentration than formula, but iron in breast milk is more bioavailable (50% vs. 10%).
  • Iron supplementation
    • 1 mg/kg/24 h for infants who are exclusively breastfed beyond 4 months
    • 2 mg/kg/24 h by 1 month of life for low-birth-weight and premature infants who are breastfed because of poor iron stores and increased growth rate
    • Iron-fortified formula for the first 12 months of life for infants who are not breastfed
    • Encourage iron-enriched cereal when infants are started on solid food.
  • Screen hemoglobin level at periodic intervals.
    • The American Academy of Pediatrics (AAP) recommends screening at 12 months, 1 to 3 years old, and adolescents as well as annually in menstruating females.
    • Centers for Disease Control and Prevention (CDC) recommends screening high-risk groups annually between ages 2 and 5 years and all menstruating women every 5 to 10 years.

Pathophysiology

  • Iron is required for oxygen transport by hemoglobin.
  • Iron absorption and distribution is regulated by hepcidin, a peptide hormone secreted by liver, macrophages, and adipocytes.
  • Iron is absorbed primarily in the duodenum.
  • Iron deficiency develops because of an inadequate supply or increased demand for iron or a combination of these.
  • Sequential stages of iron deficiency
    • Depletion of iron stores: reflected by low serum ferritin and absent bone marrow stores
    • Iron-deficient erythropoiesis: near-normal number of red blood cells (RBCs) produced, but they have abnormal hemoglobin synthesis with wide distribution in RBC size
    • Iron deficiency anemia: microcytosis evident

Etiology

  • Causes of inadequate supply include dietary deficiency and malabsorption.
    • Dietary deficiency in infants and young children results from introduction of cow’s milk prior to age 12 months, exclusive breastfeeding beyond age 6 months without iron supplementation, and excessive cow’s milk intake (>24 oz/24 h).
    • Malabsorption results from surgical resection of intestine or celiac disease.
    • Certain foods impair iron absorption (tannins in tea and coffee, phytates).
  • Causes of increased demand include rapid growth and blood loss.
    • Periods of rapid growth include infancy (especially low-birth-weight and premature infants) and adolescence.
    • GI blood loss is most common and includes cow’s milk enteropathy (seen in infants), inflammatory bowel disease (IBD), and bleeding from Meckel diverticulum.
  • Other etiologies of blood loss include perinatal loss, menorrhagia, pulmonary hemosiderosis, and hematuria.
  • Several studies showed an association of obesity and iron deficiency; exact pathophysiologic mechanisms for this association are still under investigation.

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