Three White Coats

Lipids are a diverse group of water-insoluble molecules that, among other substances, includes fats (triglycerides), waxes, fatty acids, cholesterol, and fat-soluble vitamins. Lipids have important and varied physiological functions: they serve as an integral part of cell membranes (cholesterol, phospholipids); as an energy source (triglycerides i.e. fats); as enzyme helpers or co-factors (fat soluble vitamins); and as signaling molecules that affect vital cellular processes, such as growth or survival (fatty acids, eicosanoids, steroids). However, when present in excess in blood, some lipids, namely triglycerides and cholesterol, can lead to serious cardiovascular complications such as a heart disease, heart attack or stroke.

 

Lipid profile (lipid panel) is a test that determines the levels of triglycerides and cholesterol in blood. It is part of the standard physical exam and is helpful in evaluating a person’s cardiovascular risk.

 

Like all lipids, triglycerides and cholesterol need help to move through water-based blood. Lipoproteins, particles composed of lipids and water-soluble proteins, enable their transport through blood. There are several types of lipoproteins, differing in composition and physical characteristics:

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• Chylomicrons, sometimes also called ultra low density lipoprotein, ULDL

• Very low density lipoprotein, VLDL

• Low-density lipoprotein, LDL

• Intermediate density lipoprotein, IDL

• High-density lipoprotein, HDL

 

Triglycerides are primarily contained within chylomicrons and VLDL particles, while LDL particles carry majority of cholesterol. LDL particles deposit cholesterol into the cells and tissues, while HDL particles remove it and bring it to the liver for elimination. Because cholesterol deposits can cause blockages in blood vessels that can lead to a heart attack or stroke, we refer to cholesterol within LDL particles as “bad” and to the one within HDL particles as “good” cholesterol (cholesterol is the same in these particles, but its effect on our health is not).

 

A standard lipid panel provides information on the levels of:

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• Triglycerides contained in all lipoprotein particles

• Total cholesterol – cholesterol contained within all lipoprotein particles

• HDL-C – cholesterol found within HDL particles, “good cholesterol”

• LDL-C – cholesterol found within LDL particles, “bad cholesterol”

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High levels of triglycerides and particularly LDL-C have been associated with an increased risk of cardiovascular disease.  On the other hand, high levels of HDL-C seem to lower the cardiovascular risk.