Rationale and Comments
Iron depletion is a progressive process with anemia as the final phase. Thus, screening for iron deficiency using hemoglobin will only identify the most severe cases. Moreover, hemoglobin is not specific for iron deficiency or iron deficiency anemia. Iron deficiency is one of the most common nutritional deficiencies worldwide. Prevalence of iron deficiency in U.S. women ages 12 to 49 years rose from 11% in 2003 to 14.8% in 2010. Pregnant women and young children are also high-risk groups and must be evaluated. Iron deficiency in U.S. toddlers, without anemia, is estimated at 6.6% to 15.2%.
Serum ferritin is a measure of iron stores and is the most sensitive biomarker to test for early stages of iron deficiency as well as iron deficiency anemia. Sensitivity of ferritin test is 89% for diagnosis of iron depletion compared with hemoglobin, which is only 26%. Moreover, a ferritin cut off of ≤ 30 ng/mL provides 92% sensitivity and 98% specificity for iron deficiency anemia and is the best screening test for this disorder.
Evaluating patients for iron deficiency with ferritin will identify early stage iron deficiency and will potentially result in iron therapy, preventing iron deficiency anemia. Iron deficiency anemia has been long associated with psychomotor and cognitive abnormalities but even iron deficiency without anemia has been related to negative neurodevelopmental outcomes in children.
Ferritin is an acute phase reactant, and occasionally in inflammatory conditions, ferritin levels may be normal or elevated even in the presence of iron deficiency. Additional laboratory tests (such as reticulocyte hemoglobin content, mean corpuscular volume, red cell distribution width, and additional iron studies such as percent transferrin saturation and total iron binding capacity) accompanying clinical correlation are also helpful to determine iron deficiency.
- American Society for Clinical Laboratory Science
- American Academy of Pediatrics guidelines
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