One of the essential things for the sustenance of life is cholesterol. It is this cholesterol that is responsible for creating cell membranes, bile salts, Vitamin D, nerve sheaths and sex hormones. The liver in our body is the place where this cholesterol is manufactured and circulated into the blood stream flowing across the body. Cholesterol, thus formed in the liver as a waxy fatlike compound, is a type of fat called Lipid, and cannot move of its own due to its waxy nature. This lipid fat or cholesterol is transported across the blood stream by lipid-carrying proteins that are available in the body.
The composition of the cholesterol in these lipid-carrying proteins, or lipoproteins, in the blood stream determines the level of cholesterol in the body. You might have heard about the LDL count and HDL count in the blood sample, which is used to study the cholesterol levels by the doctors.
What do the LDL and HDL refer to? By definition, LDL refers to Low-Density Lipoproteins, and HDL refers to High-Density Lipoproteins. Both LDL and HDL transport the waxy substance called cholesterol. More than two-thirds of the cholesterol is transported by the LDLs while the balance one-third is transported by the HDLs.
The LDLs transporting the cholesterol tend to deposit the waxy substance in the artery walls, while the HDLs collect the waxy substance or cholesterol from these artery walls and transport it to the liver for further metabolism and excretion from the body. The cholesterol left uncleared from the walls of the arteries might lead to atherosclerosis and increases the risk of contracting heart disease.
It is in this context that LDL, which deposits cholesterol in the artery walls, is referred to as bad cholesterol and the HDL, which collects the cholesterol from the artery walls for ultimate disposition, is referred to as good cholesterol.
The amount of cholesterol in the blood is determined by a blood cholesterol test. The test results are expressed in terms of milligrams (mg) of cholesterol per deciliter (dl). Broadly, the blood cholesterol level, including both LDL and HDL, below 200 mg/dl is considered desirable. If the value is more than 200 mg/dl, then individual measurements of LDL and HDL are taken for analysis. LDL level should be below 130 mg/dl to be considered normal. LDL level having a reading above 130 mg/dl and below 159 mg/dl is classified to be moderately high, and any reading in excess of 160 mg/dl has been classified as risky, and prone for coronary artery disease and even heart attacks.
As far as the level of HDL is considered, any reading above 45 mg/dl is considered safe. The higher it is than 45 mg/dl, the better it would be for the health of the person. In addition to the individual LDL and HDL measurements, doctors also calculate the LDL/HDL ratio by dividing the total cholesterol by the HDL figure for assessing the cardiovascular risk of cholesterol. The desirable ratio should be less than 4.5 for eliminating the risk of cholesterol.