10-year-old girl has exhibited increasing sluggishness with poorer performance in school over the past year. She has not had increased numbers of infections. The child now complains of headaches. A physical examination shows no hepatosplenomegaly or lymphadenopathy. A CBC shows: Hgb 11.8 g/dL, Hct 33.9%, MCV 71 fL, platelet count 293,000/microliter, and WBC count 8160/microliter. Examination of her peripheral blood smear shows basophilic stippling of erythrocytes. The serum haptoglobin is 5 mg/dL. Which of the following laboratory test findings is most likely to be present in this girl Elevated free

10-year-old girl has exhibited increasing sluggishness with poorer performance in school over the past year. She has not had increased numbers of infections. The child now complains of headaches. A physical examination shows no hepatosplenomegaly or lymphadenopathy. A CBC shows: Hgb 11.8 g/dL, Hct 33.9%, MCV 71 fL, platelet count 293,000/microliter, and WBC count 8160/microliter. Examination of her peripheral blood smear shows basophilic stippling of erythrocytes. The serum haptoglobin is 5 mg/dL. Which of the following laboratory test findings is most likely to be present in this girl Elevated free