Normal hemoglobin may also be thalassemia. That is, a normal hemoglobin does not exclude thalassemia because thalassemia is a genetic disorder. Due to a genetic defect that leads to impaired synthesis of the globin peptide chain, the patient will develop symptoms of hemolytic anemia. Thalassemia is clinically divided into three types according to the severity of the disease: one is mild thalassemia, the second is moderate thalassemia, and the last is severe thalassemia. In mild thalassemia, the hemoglobin concentration may be normal, that is, in mild thalassemia, the hemoglobin concentration is within the normal range, but the average volume of red blood cells and the average hemoglobin amount are reduced. In moderate and severe thalassemia, the hemoglobin concentration is significantly lower, as well as the average erythrocyte volume and the average erythrocyte hemoglobin amount.