Final answer:
Methotrexate can cause macrocytic anemia by interfering with folate metabolism, critical for DNA synthesis. Treatment typically involves supplementation with vitamins B12 and folate, depending on the cause.
Step-by-step explanation:
Drugs such as Methotrexate can cause macrocytic anemia by inhibiting the enzyme required for folate conversion, which is necessary for DNA synthesis. The treatment for such anemia typically involves supplementation with vitamin B12 and folate, contingent upon the underlying cause. Anemias related to faulty or decreased RBC production, such as sickle cell anemia, iron deficiency anemia, vitamin deficiency anemia, and diseases of the bone marrow and stem cells, can affect the size of red blood cells, leading to variations like macrocytic, microcytic, or normocytic cells.
For those anemias caused by nutritional deficiencies, diet modifications and supplements are often prescribed. In the case of megaloblastic anemia, which involves a deficiency of vitamin B12 and/or folate, addressing the dietary lack of these nutrients is key. In contrast, drug-induced macrocytic anemia, such as that caused by Methotrexate, usually requires cessation of the drug or counteraction of its effects with appropriate vitamin supplementation.