Overview of cholesterol and lipid disorders

[Marquetta]

Important fats (lipids) found in the blood are

Cholesterol
Triglycerides

Cholesterol is an essential component of cell membranes, of brain and nerve cells, and of bile, which helps the body absorb fats and fat-soluble vitamins. The body uses cholesterol to make vitamin D and various hormones, such as estrogen , testosterone , and cortisol . The body can produce all the cholesterol that it needs, but it also obtains cholesterol from food.
Triglycerides, which are contained in fat cells, can be broken down, then used to provide energy for the body’s metabolic processes, including growth. Triglycerides are produced in the intestine and liver from smaller fats called fatty acids. Some types of fatty acids are made by the body, but others must be obtained from food.
Fats, such as cholesterol and triglycerides, cannot circulate freely in the blood, because blood is mostly water. To be able to circulate in blood, cholesterol and triglycerides are packaged with proteins and other substances to form particles called lipoproteins.
There are different types of lipoproteins. Each type has a different purpose and is broken down and excreted in a slightly different way. Lipoproteins include

Chylomicrons
Very low density lipoproteins (VLDL)
Low-density lipoproteins (LDL)
High-density lipoproteins (HDL)

Cholesterol transported by LDL is called LDL cholesterol, and cholesterol transported by HDL is called HDL cholesterol.
The body can regulate lipoprotein levels (and therefore lipid levels) by increasing or decreasing the production rate of lipoproteins. The body can also regulate how quickly lipoproteins enter and are removed from the bloodstream.
Levels of cholesterol and triglycerides vary considerably from day to day. From one measurement to the next, cholesterol levels can vary by about 10%, and triglyceride levels can vary by up to 25%.
Lipid levels may be

Too high (dyslipidemia)
Too low (hypolipidemia)

Lipid levels may become abnormal because of changes that occur with aging, various disorders (including inherited ones), use of certain drugs, or lifestyle (such as consuming a diet high in saturated fat, being physically inactive, or being overweight).