WBR0486
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathophysiology, MainCategory::Pharmacology |
| Sub Category | SubCategory::Hematology |
| Prompt | [[Prompt::A 1 year old boy is brought to the pediatrics outpatient clinic for 4 weeks of pallor and excessive sleepiness. His mother reports normal development and feeding habits. Physical exam is significant for hepatomegaly and marked pallor. Blood tests show a hemoglobin of 7.2 g/dL with microcytosis and anisocytosis. Futher testing reveals a mutation in the ALAS2 gene. What is the most appropriate treatment for this patient?]] |
| Answer A | AnswerA::Chronic transfusions |
| Answer A Explanation | AnswerAExp::Chronic transfusions are used to treat patients with thalassemia major or other bone marrow failure syndromes. |
| Answer B | AnswerB::Deferioxamine |
| Answer B Explanation | AnswerBExp::Deferioxamine is used in the treatment of iron overload following chronic transfusions. Although sideroblastic anemia is associated with iron overload, iron chelation is not the first line of therapy. |
| Answer C | AnswerC::Pyridoxine |
| Answer C Explanation | AnswerCExp::Pyridoxine or vitmain B6 is a cofactor in the rate limiting step of heme synthesis and it successfully improves the anemia in 75% of patients with congenital sideroblastic anemia. |
| Answer D | AnswerD::Folic Acid and Vitamin B12 |
| Answer D Explanation | AnswerDExp::Folic Acid and Vitamin B12 are usually given to treat megaloblastic anemia. |
| Answer E | AnswerE::Iron replacement |
| Answer E Explanation | AnswerEExp::Iron replacement is used to treat patients with iron deficiency anemia. |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::Sideroblastic anemia is an inherited disease in which the bone marrow produces ringed sideroblasts due to defective hemoglobin synthesis and iron accumulation. Classically, sideroblastic anemia is an X-linked disease although other patterns of inheritance can be encountered. The disease is due to a deficiency in ALA synthase, the rate limiting step in heme synthesis, secondary to a mutation in the ALAS2 gene. This leads to a decrease in heme synthesis and accumulation of non-heme iron around red blood cells giving them the characteristic ringed sideroblasts appearance. Treatment is usually with pyridoxine (vitamin B6) which is a cofactor in the reaction catalyzed by ALA synthase. It is effective in improving the anemia in around 75% of patients.
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| Approved | Approved::No |
| Keyword | WBRKeyword::Sideroblastic anemia, WBRKeyword::Pyridoxine, WBRKeyword::Vitamin B6 |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |