Comparative effectiveness of zinc protoporphyrin and hemoglobin concentrations in identifying iron deficiency in a group of low-income, preschool-aged children: practical implications of recent illness.

OBJECTIVE: The goal was to assess the influence of recent infection on screening tests for iron depletion (zinc protoporphyrin and hemoglobin) among low-income, preschool-aged children. METHODS: This cross-sectional study was conducted at community sites and ambulatory care clinics in Hartford, Connecticut, and included 180 preschool-aged children. Iron depletion was defined as serum ferritin levels of < or = 15 microg/L. Recent illness was defined by parent or guardian (caretaker) report or evidence of elevated C-reactive protein concentrations. History of anemia was determined through medical records review. Sensitivity, specificity and positive predictive values of hemoglobin and zinc protoporphyrin were calculated overall and for children with and without recent illness. RESULTS: At enrollment, more than one half of the children had a recent illness, and 57.5% had a history of anemia. More than one third had iron depletion. Serum ferritin levels were significantly higher among recently ill children. Secondary to recent illness, the positive predictive value of elevated zinc protoporphyrin, but not low hemoglobin, was reduced significantly. Zinc protoporphyrin levels of >69 micromol/mol heme identified significantly more iron-deficient children. CONCLUSIONS: Compared with anemia, elevated zinc protoporphyrin levels identified significantly more iron-deficient children. Recently ill children were one half as likely to have low serum ferritin levels, compared with children without recent illness. The negative effect of recent illness on the positive predictive value of zinc protoporphyrin when ferritin is used to determine iron status has many practical implications.

Managing anemia in low-income toddlers: barriers, challenges and context in primary care.

Iron-deficiency remains a concern among low-income toddlers in the U.S. This formative study describes how primary care providers serving high-risk 1- to 3-year-old children in an urban ambulatory care setting approach anemia. Data collection included a retrospective review of randomly selected medical records (n=264) and semi-structured interviews with clinicians (n=41). Thirty-eight percent of the children presented with anemia (Hgb < 11.0 g/dl) at least once between 12 and 36 months of age. Just under half of these children were treated for anemia. Follow-up laboratories for iron-treated children were completed within 35 days in 16% of cases (median: 3 months). Interviews identified four key themes (iron-deficiency, communication, poverty, system) running through the two major categories of prevention and treatment. Treatment cut-points were variable. While providers felt clinically comfortable with anemia, they felt burdened and challenged by follow-up. Communication and system barriers weighed most heavily on perceived treatment outcomes.