Low density refers to LDL and high density refers to HDL. Total cholesterol is not usually the sum of HDL and LDL.
Total cholesterol is the sum of the cholesterol contained in the various lipoproteins in the blood, and cholesterol is an important raw material for the synthesis of sex hormones, adrenocorticotropic hormone, bile acids, vitamin D, and other substances, as well as a major component of cell membranes.
HDL is a complex of cholesterol, proteins, and phospholipids synthesized in the small intestine and liver; LDL is a complex of cholesterol, phospholipids, and proteins, and is mainly formed through the isomerization of very-low-density lipoproteins.
Therefore, total cholesterol is usually not the sum of HDL and LDL.
It is advisable to visit a hospital and ask your doctor to make a judgment when you have a dyslipidemia.