Anemia requires an initial routine blood test, which is a complete blood count. If it indicates a reduction in red blood cell count and a significant decrease in hemoglobin, it suggests anemia. Once anemia is indicated by the complete blood count, further tests are guided by the size of the red blood cell volume. If it is microcytic anemia, common types include iron deficiency anemia and anemia of chronic disease, and tests such as serum iron, ferritin, and tumor markers are needed. If it is normocytic anemia, a bone marrow biopsy is required to rule out aplastic anemia, multiple myeloma, etc. If it is macrocytic anemia, tests for folate and vitamin B12 are needed to exclude myelodysplastic syndrome and megaloblastic anemia, among others.