Atherosclerosis of aorta and changes of its indexes. Atherosclerosis index is an accurate index to measure arteriosclerosis, and the normal value should be less than 4. Subtract high-density lipoprotein from serum total cholesterol, and then divide it by high-density lipoprotein to calculate the arteriosclerosis index. A value less than 4 indicates that the degree of arteriosclerosis is not serious or decreasing. The smaller the value, the lower the risk of arteriosclerosis. Greater than or equal to 4 indicates that arteriosclerosis has occurred. The greater the value, the higher the degree of arteriosclerosis or the incidence of cardiovascular and cerebrovascular diseases.