What is Cholesterol?

Keeley Schwartz

What are LDL and HDL?

HDL is a type of cholesterol that stands for high density lipoprotein. This cholesterol is usually considered the "good cholesterol."

LDL is a type of cholesterol that stands for low density lipoprotein. It is usually considered the "bad cholesterol."

How do LDL and HDL differ structurally and functionally?

LDL structure is composed of around 50% cholesterol and 25% protein. LDL molecules are much smaller and denser than HDL molecules. Since they are smaller and less dense, they are more likely to go through oxidation and accumulate on arterial walls as plaque.

The main function of LDL is to carry cholesterol to different parts of the body. Since it takes cholesterol to different parts.

HDL structure is around 20% cholesterol and 50% is protein. HDL molecules are larger and more buoyant than LDL molecules. They are less likely to cause plaque buildup because of their structure.

HDL's main function is to take cholesterol from your heart and other organs to the liver to be disposed of. This is why it is considered to be the "healthy cholesterol." Some cholesterol is good so only the excess is carried away and disposed of.

What other molecules in a patient’s blood are monitored along with LDL and HDL?

- blood sugar level
- total cholesterol

Why do doctors monitor the concentrations of LDL and HDL in patients’ blood?

During a blood test, LDL and HDL are both monitored along with other things because they are used to help evaluate the patient's risk of heart disease. Whether more cholesterol is being taken to or from cells can be determined during a blood test.

How are the concentrations of LDL and HDL associated with the risk for heart disease and associated disorders?

An excess of LDL can result in plaque buildup on arterial walls which can ultimately result in atherosclerosis. That is the hardening of the arteries and can lead to heart diseases like a heart attack or stroke. Unlike LDL, higher HDL levels can actually lower the risk of heart disease.

What do the results of a cholesterol test mean? How do patients interpret each value?

The results of the cholesterol test show whether your cholesterol levels are healthy. Patients can interpret each value based upon scales for each molecule. For total cholesterol, less than 200 mg/dL is considered healthy, while 200 - 239 mg/dL is borderline high and 240 mg/dL is high. For HDL, less than 40 mg/dL is low for men and less than 50 mg/dL is low for women, and 60 mg/dL is considered healthy. For LDL, less than 100 mg/dL is optimal, 100 - 129 mg/dL is near or above optimal, 130 - 159 mg/dL borderline high, 160 - 189 mg/dL is high, and 190 mg/dL is very high. For triglycerides, less than 100 mg/dL is optimal, less than 150 mg/dL is normal, 150 - 199 mg/dL is borderline high, 200 - 499 mg/dL is high, and 500 mg/dL and above is very high. These are the ranges to interpret the cholesterol test, but other factors such as age, can affect the ranges, and your doctor can take these factors into account, and adjust the results.

What can patients do to change the levels of LDL and HDL in their blood?

Several things can be done to change the levels of both LDL and HDL in your blood. A healthy diet with reduced fat and cholesterol will increase HDL levels and decrease LDL levels. Saturated fat intake should be limited 7% or less of total calories, cholesterol should be 200mg per day or less, and Omega 3 fatty acids will increase HDL levels. It has been found that physical activity can raise HDL levels 5%. The activity needs to be consistent with at least 30 minutes a day for 5 days a week. An estimated every six pounds that are lost can increase HDL by one and lower LDL by one. Medication can also be used with the other things above.

How does intake of unsaturated, saturated, and trans fats affect cholesterol levels and overall health?

Unsaturated - help reduce LDL, and lower risk of heart disease and stroke; provide nutrients to help develop and maintain cells
Saturated - raises the level of cholesterol in blood; high levels can increase the risk of heart disease and stroke
Trans - partially hydrogenated, raises LDL, which can clog arteries and cause heart disease, and lower HDL

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