Anemia

Chapter 4 ANEMIA


Jonathan M. Wong



General Discussion


Anemia is a frequent laboratory abnormality in children, affecting as many as 20% of children in the United States and as many as 80% of children in developing countries. Anemia is defined as a decreased concentration of hemoglobin and red blood cell (RBC) mass compared with age-matched controls. Age-specific blood cell indices are outlined below in Table 4-1.



Table 4-1 Age-Specific Blood Cell Indices

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The physiologic anemia of infancy is often confused with a pathologic condition. During the first weeks of life, erythropoietin synthesis abruptly decreases, resulting in a relative anemia. In the ensuing 6 to 8 weeks, the hemoglobin reaches a low point of 9 to 11 g/dL in term infants. The hemoglobin may reach a low point of 7 to 9 g/dL in premature infants. Erythropoietin production is then stimulated, and the hemoglobin level returns to normal. This physiologic anemia does not require work-up unless it is lower than the expected range.


Anemia varies with sex as well as race. African-American children have a lower normal value than their Caucasian counterparts, and glucose-6-phosphate dehydrogenase (G6PD) deficiency is far more common in male than in female children.


Most children with anemia are asymptomatic and have an abnormal hemoglobin level detected at routine screening. A child may present with pallor, fatigue, or jaundice if the anemia is severe or acute.


Anemia usually results from decreased production of RBCs, increased destruction of RBCs, or blood loss. Erythropoietin is the main hormonal regulator of RBC production. In the fetus, it comes from the monocyte/macrophage system of the liver, and postnatally is produced in the peritubular cells of the kidneys.



Medications Associated with Anemia




Acetylsalicylic acid (in patients with G6PD deficiency)


Antibacterials (in patients with G6PD deficiency)


• Chloramphenicol

• Nalidixic acid

• Nitrofurantoin

• Sulfonamides

Antimalarials (in patients with G6PD deficiency)


• Chloroquine

• Paraquine

• Primaquine

• Quinacrine

Aspirin


Chemotherapy agents


Clopidogrel


Human immunodeficiency virus (HIV) medications


Methylene blue (in patients with G6PD deficiency)


Phenacetin (in patients with G6PD deficiency)


Phenazopyridine (in patients with G6PD deficiency)


Probenacid (in patients with G6PD deficiency)


Vitamin K analogues (in patients with G6PD deficiency)


Warfarin



Causes of Anemia




Decreased red cell production


Marrow failure

• Aplastic crisis (e.g., parvovirus B19 infection)

• Diamond-Blackfan syndrome

• Fanconi anemia

• Transient erythroblastopenia of childhood

Impaired erythropoietin production

• Chronic inflammatory diseases

• Hypothyroidism

• Protein malnutrition

• Renal failure

Defects in red cell maturation

• Folate deficiency

• Iron deficiency anemia

• Pure red cell aplasia

• Sideroblastic anemia

• Vitamin B12 deficiency

Increased red cell destruction


Extracellular

• Autoimmune hemolytic anemias

• Drugs

• Hemolytic uremic syndrome (HUS)

• Mechanical injury from cardiac valvular defects

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Jun 18, 2016 | Posted by in PEDIATRICS | Comments Off on Anemia

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