NADH-MetHb reductase activity was measured using cyanogenic methemoglobin as a substrate, or dichlorophenol-indophenol as a substrate to determine yellow delivery enzyme activity, or cytochrome b5 as a substrate to determine b5R activity. It should be emphasized that the results in the test tube (at high substrate concentrations) do not exactly reflect the degree of reduced catalytic efficiency in living cells (at low substrate concentrations) due to the different mechanisms of action of different genetic variants. The tests for abnormal cellular enzyme activity are: 1. Routine blood test Routine blood test is the most general and basic blood test. Routine blood test is usually taken from peripheral blood for examination, such as blood from fingertip and earlobe area. After the blood cell analysis instrument, the computer reports the results, and this item has become a practice to examine patients. Blood consists of two major parts, liquid and tangible cells, and routine blood tests are performed on the cellular part of the blood. Blood has three different functions of cells – red blood cells (commonly known as red blood cells), white blood cells (commonly known as white blood cells), and platelets. Diseases are determined by observing changes in number and morphological distribution. It is one of the common auxiliary tests used by doctors to diagnose the disease 2. Antibody-dependent cells K cells are a class of lymphocytes that are neither T nor B. It has no surface Ig, but has Fc receptor, and can perform the function of killing target cells with the participation of specific antibodies. When the antigen on the surface of the target cell binds to the corresponding antibody, the Fc segment of the antibody binds to the surface of the K cell, forming an antibody bridge to contact the target cell and the killing effect occurs, so K cells are also called antibody-dependent cytotoxic cells. This killing effect is non-specific and does not require the participation of complement.