When a patient suspects that he or her doctor suspects that the patient has transformed from hepatitis B to hepatocellular carcinoma, some auxiliary tests are needed. The routine examinations include CT, ultrasound, MRI and other imaging examinations and serological tests. Other tests include ferritin (Fer) and serum enzymes (γ-GT and isoenzymes, alkaline phosphatase and isoenzymes, pyruvate kinase and isoenzymes, etc.). Methemoglobin is commonly used clinically as a test for hepatocellular carcinoma and germ cell carcinoma (non-seminomatous cell carcinoma) and for monitoring people at high risk for liver cancer. In primary hepatocellular carcinoma, 70% to 90% of patients have elevated methemoglobin, and the level of serum methemoglobin value correlates with tumor size. In the diagnosis of hepatocellular carcinoma, 400 μg/ml is generally used as the diagnostic threshold for primary hepatocellular carcinoma, but some patients with primary hepatocellular carcinoma also have AFP within the normal range. It is generally believed that the level of methemoglobin is related to the degree of tumor differentiation. Therefore, clinical detection of methemoglobin value is meaningful for the estimation of disease and evaluation of treatment effect. Although methemoglobin is a better indicator for early hepatocellular carcinoma diagnosis, its clinical significance is still limited. Some patients with hepatocellular carcinoma have serum methemoglobin concentrations consistently ranging from 20 to 200 μg/ml, which is difficult to make early diagnosis. Since 30%-40% of patients with hepatocellular carcinoma have negative serum methemoglobin test, other markers also have some reference value for patients with methemoglobin negative hepatocellular carcinoma, such as serum biochemical liver function index γ-glutamyl transferase (r-GT) is significantly elevated in the serum of patients with active hepatocellular carcinoma.