To prevent this complication, patients also require chelation therapy with one of the following: However, because each unit of pRBCs contains 200 to 250 mg of iron, chronic transfusion can cause iron overload (secondary hemochromatosis). Patients with β-thalassemia major are transfusion-dependent, meaning that they require chronic packed red blood cell (pRBC) transfusions. Although not mentioned in this question, a peripheral blood smear often shows target cells. Additional findings can include jaundice and splenomegaly (caused by splenic hemolysis of erythrocytes) and skeletal abnormalities (caused by extramedullary hematopoiesis). Affected patients present at approximately 6 to 12 months of age (when hemoglobin A synthesis begins) with fatigue and pallor caused by microcytic anemia. Newborn patients with β-thalassemia major typically are asymptomatic because hemoglobin F (fetal hemoglobin) predominates during the first few months of life. In these patients, hemoglobin electrophoresis shows increased concentrations of hemoglobin A2 (composed of two α chains and two δ chains) and hemoglobin F (composed of two α chains and two γ chains). However, mutations in both β-globin genes result in absent β-globin gene expression, a condition referred to as β-thalassemia major. Hemoglobin A normally is composed of two α chains and two β chains. She also will require iron chelation therapy with a medication such as deferoxamine or deferasirox to prevent iron overload. This patient’s laboratory findings are consistent with β-thalassemia major, and she will be transfusion-dependent throughout her life. Hemoglobin electrophoresis: Absent hemoglobin A, ↑ Hemoglobin A2, ↑ Hemoglobin FĬhelation therapy (eg, deferoxamine) to prevent iron overload Microcytic anemia with target cells on peripheral smear Splenic hemolysis of erythrocytes → jaundice, dark urine, splenomegalyĮxtramedullary hematopoiesis → skeletal abnormalities Succimer therapy Answer and Explanation β-Thalassemia Major In addition to chronic transfusions of packed red blood cells, which of the following medications is most likely to improve long-term survival in this patient?Į. Abdominal examination shows splenomegaly. Cardiopulmonary examination shows no abnormalities. Physical examination shows moist mucous membranes. Today, she is alert and playing with her mother. She lives with her parents in a single-family home that was built in 2010. She is breast-fed exclusively and feeds appropriately. Since discharge, she has not had fatigue. Laboratory studies on admission showed microcytic anemia and increased concentrations of hemoglobin A2 and hemoglobin F, and the patient received multiple transfusions of packed red blood cells during her hospital stay. Your First Free Step 2 Sample QuestionĪ 7-month-old girl is brought to the office for follow-up examination 1 week after admission to the hospital because of fatigue and severe anemia. Below is a free USMLE Step 2 CK sample question so you can see what we mean. That’s why we have high-yield practice questions written and screened by high-performing physician authors that are updated on a regular basis to ensure our SmartBanks stay up-to-date with exam blueprint changes. At TrueLearn, we understand that it’s all about the content. Plus, if you're not happy with any new tutor, we'll gladly refund the cost of your first hour.See why TrueLearn is a trusted resource for thousands of medical students. Wyzant helps more students find face to face lessons, in more places than anyone else. If you are looking to learn a subject similar to USMLE Step 2, tap into the nation’s largest community of private tutors. Get 1-to-1 learning help through online lessons. Find Online Tutors in Subjects related to USMLE Step 2.
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