A 6-year-old girl with sickle cell anemia (HbSS), not on hydroxyurea, presents with a temperature of 39.4°C (103°F), cough, and respiratory distress. A chest x-ray reveals a new infiltrate in the left lower lobe. Continuous pulse oximetry shows her saturation has dropped to 91%. In addition to antibiotics and oxygen, which intervention is most critical for aborting a rapidly progressing acute chest syndrome?
A 4-month-old infant is admitted for failure to thrive, persistent diarrhea, and seizures. Labs reveal a severe megaloblastic anemia with very low serum and cerebrospinal fluid (CSF) folate levels. The CSF-to-serum folate ratio is < 1. High-dose parenteral folate therapy is initiated. This clinical presentation is most consistent with which rare inherited disorder?
A 1-year-old child of African descent is diagnosed with homozygous hemoglobin C disease (HbCC) through newborn screening. His parents ask about the expected clinical course. Which of the following is the most accurate description of this condition?
A 4-year-old boy with a known diagnosis of pyruvate kinase deficiency is seen for a follow-up visit. His parents are surprised that despite having a hemoglobin of 8 g/dL, he remains very active and playful. Which biochemical alteration primarily explains his excellent clinical tolerance to chronic anemia?
A 3-week-old neonate presents with severe jaundice (total bilirubin 22 mg/dL) and anemia (hemoglobin 8.0 g/dL), requiring exchange transfusion. The direct antiglobulin (Coombs) test is negative. The peripheral smear shows numerous spherocytes. The parents are healthy and have no history of anemia. Which of the following is the most likely underlying genetic basis for this severe neonatal presentation of hereditary spherocytosis?
An 8-year-old boy with known sickle cell disease develops an acute drop in his hemoglobin from a baseline of 8.5 g/dL to 4.0 g/dL over several days, accompanied by fever and profound reticulocytopenia. This “aplastic crisis” is most clearly documented to be caused by which virus?
A 6-year-old boy of Mediterranean descent is brought to the emergency department with acute-onset jaundice and dark urine. This started 48 hours after he began taking a fluoroquinolone for a severe skin infection. An initial screening test for Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency returns in the low-normal range, despite a very high reticulocyte count. What is the most appropriate next step in management?
A 12-year-old girl with non-transfusion-dependent β-thalassemia intermedia presents with progressive shortness of breath and lower extremity edema. An echocardiogram shows signs of pulmonary hypertension. She has not had a splenectomy. Which of the following is the most likely contributing factor to the development of pulmonary hypertension in this patient?
An 8-year-old child presents with acrocyanosis and mild jaundice two weeks after recovering from a respiratory illness diagnosed as atypical pneumonia. Lab work reveals red blood cell agglutination on the peripheral smear, and the direct antiglobulin test is positive for complement only. This presentation of secondary cold agglutinin disease is most frequently associated with which infectious agent?
A 3-year-old presents with bloody diarrhea, which is followed five days later by acute kidney injury, thrombocytopenia, and fragmentation hemolytic anemia. A stool culture is positive for Escherichia coli O157. His ADAMTS13 activity level is confirmed to be normal. Which of the following interventions is the cornerstone of management for this child’s condition?
