102 video review lessons. Review AP US History by watching and listening to over 18 hours worth of videos carefully coordinated to the AP US History syllabus. 290 AP US History practice questions. Test your understanding of each concept without having to take an entire AP US History practice exam. Customized AP US History study plan.
In fact the most common cause of microcytic anemia is iron deficiency, and in low risk patients physicians often confirm the diagnosis of iron deficiency as the cause by a good response to iron therapy.
This leads to continuing cell growth without division, which presents as macrocytosis. Megaloblastic anemia has a rather slow onset, especially when compared to that of other anemias. The defect in red cell DNA synthesis is most often due to hypovitaminosis, specifically a deficiency of vitamin B12 and/or folic acid.egaloblastic anemia not due to hypovitaminosis may be caused by antimetabolites that poison DNA production directly, such as some chemotherapeutic or antimicrobial agents (for example azathioprine or trimethoprim).