A 48-year-old woman comes to the physician because of a 4-month history of lightheadedness, intermittent headaches, and easy bruising. Five months ago, she was treated for an episode of thrombophlebitis. Physical examination shows multiple bruises on her limbs. Laboratory studies show a platelet count of 900,000/mm3 and elevated levels of serum lactate dehydrogenase and uric acid. Treatment with a medication is begun that is also used in the treatment of sickle cell disease. Which of the following mechanisms is most likely responsible for the beneficial effect of this drug in sickle cell disease?

Question

Quizplus · Accepted Answer

Eductional Objective: Fetal hemoglobin (HbF) does not contain Beta-globin chains, the mutated component in sickle cell anemia hemoglobin (HbS). Hydroxyurea alters the genetic expression of Beta-globin chains, with Gamma-globin chains being produced instead (i.e., HbF created in place of HbS or HbA). RBCs containing a higher concentration of HbF do not sickle. Therefore, the number of hemolytic and vaso-occlusive episodes decreases, making hydroxyurea the first-line treatment for sickle cell anemia. Hydroxyurea also has a cytoreductive action, blocking DNA synthesis and cell division by inhibiting ribonucleotide reductase. This makes it a potent antimetabolite and a useful drug in the treatment of myeloproliferative diseases, as this patient has.

A 48-Year-Old Woman Comes to the Physician Because of a 4-Month