Middle Eastern Adolescent With Macrocytic Anemia

A 14-year-old previously healthy adolescent female was referred to the emergency department for complaints of fatigue and weakness. She had been seen 1 day prior at her primary care physician's office and was found to have a hemoglobin level of 6.7 g/dL. Over the past month, she had been feeling " weak " and " looking more pale. " She was born and raised in Iraq, of Chaldean eth-nicity, and recently moved to the United States with her family. When she was 2½ years old she was diagnosed with anemia. A blood transfusion was attempted but discontinued because of a rash. Her mother was told that her stomach " couldn't suck out the iron, " and the patient was placed on folic acid and vitamin B 12 for treatment of her anemia. However, she only took the medication when she felt fatigued, and since moving to the United States, she had not taken any medication. Her last men-strual period was 4 days prior to presentation. Her men-strual cycles occurred regularly every 4 weeks and generally lasted 2 days in length. In the emergency department, she was afebrile, with a heart rate of 115 bpm and blood pressure of 119/74 mm Hg. She was alert and interactive. Physical examination was remarkable for pallor, but otherwise normal without jaundice, adenopathy, or hepatosplenomegaly. Initial laboratory analysis as depicted in Table 1 revealed pan-cytopenia with macrocytic anemia and reticulocytosis. Blood smear showed polychromasia with target cells, teardrop cells, schistocytes, and spherocytes. Her lactate dehydrogenase was elevated at 1870 U/L (100-275), and iron studies showed a decreased iron level at 20 µg/dL (30-160), normal total iron binding capacity of 294 µg/dL (228-417), and decreased % saturation of 7% (15% to 55%). A vitamin B 12 level of 106 pg/mL (271-870) and a folate level of 17.3 ng/mL (>5.4) were obtained. Her comprehensive metabolic panel was within normal limits. On further evaluation in the hematology clinic, serum homocysteine and serum methylmalonic acid (MMA) levels were both elevated at 35 µmol/L (4-14) and 25 nmol/mL (<0.40), respectively, and a red blood cell folate level was normal at 582 ng/mL (>280), supporting the diagnosis of vitamin B 12 deficiency. Anti-parietal cell antibody test for pernicious anemia was negative, and she was diagnosed with a presumed genetic defect causing intrinsic factor deficiency. She was placed on weekly vitamin B 12 1000 µg intra-muscularly as well as a course of …