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

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.