Thalassemia firstly requires genetic diagnosis through a series of techniques such as DNA restriction endonuclease map PCR, which identify the genotype of thalassemia.

Secondly, hemoglobin electrophoresis needs to be completed. Through complete hemoglobin electrophoresis, it can discriminate between silent gene carriers and those with thalassemia, hemoglobin H disease, and hemoglobin Bart's hydrops fetalis syndrome. Additionally, a significant increase in hemoglobin A2 in overt thalassemia also has certain specificity.

Thirdly, a complete bone marrow picture is necessary, which will match the bone marrow picture of hemolytic anemia. There is pronounced erythroid hyperplasia, positive iron staining, and an increase in sideroblastic erythroblasts.

Fourthly, a complete blood count is needed. Different types of blood counts show different levels of hemoglobin reduction. In mild thalassemia and thalassemia traits, hemoglobin is mostly normal or mildly decreased. In severe thalassemia, hemoglobin is generally below 50 grams per liter, indicating a severe anemic state. Blood smears might show anisocytosis, poikilocytosis, and target cells. It is common to see nucleated erythrocytes and reticulocytes significantly increased, which matches the signs of hemolytic anemia.

Fifth, iron metabolism testing needs to be completed. By improving iron metabolism testing, it serves as a discriminant for silent gene carriers, as well as those with thalassemia traits and patients with mild thalassemia based on serum iron, iron saturation, and serum ferritin concentration.

Sixth, X-ray examination needs to be completed. Severe thalassemia features typical hair-on-end changes, visible as vertical striations between the trabeculae of the cortical bone in the skull X-rays, resembling upright hair and rays of sunlight.