HDL-C

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Picture Courtesy: https://blmhospital.com/2019/09/18/cholesterol-the-good-the-bad-and/

Context: HDL cholesterol is correlated with low cardiovascular disease (CV) risk, and it has been traditionally labelled as "good" cholesterol due to its negative correlation with CV disease.

About Cholesterol

• Cholesterol is a type of fat that circulates in blood. It is essential for many functions in the body, such as making hormones, vitamin D, and bile acids. However, too much cholesterol can be harmful, as it can build up in arteries and increase the risk of heart disease and stroke.
• There are two main types of cholesterol: low-density lipoprotein (LDL) and high-density lipoprotein (HDL).
  • LDL is often called the "bad" cholesterol because it carries cholesterol from the liver to the cells and tissues, where it can accumulate and form plaques.
  • HDL is often called the "good" cholesterol because it carries cholesterol from the cells and tissues back to the liver, where it can be removed from the body.
• HDL-C is the amount of cholesterol carried by HDL particles in blood. It is one of the markers that doctors use to assess cardiovascular health. Generally, higher levels of HDL-C are associated with a lower risk of heart disease, while lower levels are associated with higher risk.

How does HDL-C protect the heart?

• It helps remove excess cholesterol from your arteries, preventing or reversing plaque formation.
• It has anti-inflammatory and antioxidant properties, reducing damage to the artery walls.
• It improves the function of the endothelium, the inner lining of the arteries that regulates blood flow and clotting.
• It inhibits the oxidation of LDL, which makes it more likely to cause plaque formation.

However, not all HDL particles are equally protective. Some HDL particles may be more effective at removing cholesterol from the arteries than others. Some HDL particles may even become dysfunctional and promote inflammation and oxidation. Therefore, the quality and function of HDL may be more important than quantity.

How to measure and interpret HDL-C levels?

• HDL-C levels are measured by a blood test, usually as part of a lipid profile that also includes total cholesterol, LDL-C, and triglycerides. The normal range for HDL-C varies depending on age, gender, and other factors, but generally:
  • For men, HDL-C levels below 40 mg/dL (1.0 mmol/L) are considered low, and levels above 60 mg/dL (1.6 mmol/L) are considered high.
  • For women, HDL-C levels below 50 mg/dL (1.3 mmol/L) are considered low, and levels above 60 mg/dL (1.6 mmol/L) are considered high.
• However, these ranges are not absolute, and other factors such as family history, lifestyle, and medical conditions may affect the risk of heart disease.

Several lifestyle changes can help to increase HDL-C levels and improve cardiovascular health: Exercise regularly, eat a healthy diet, quit smoking, limit alcohol intake, manage weight, etc.

 Conclusion

• HDL-C is a marker of cardiovascular health that reflects the amount of cholesterol carried by HDL particles in the blood. Higher levels of HDL-C are generally associated with a lower risk of heart disease, while lower levels are associated with a higher risk.

PRACTICE QUESTION Q. What type of cholesterol is considered "good" and helps remove excess cholesterol from the blood? A) Low-density lipoprotein (LDL) B) High-density lipoprotein (HDL) C) Very-low-density lipoprotein (VLDL) D) Chylomicrons Answer: B Explanation: HDL, or high-density lipoprotein, is considered "good" cholesterol. HDL plays a crucial role in cardiovascular health by helping to remove excess cholesterol from the blood vessels and transporting it back to the liver for excretion. This process is part of the reverse cholesterol transport (RCT) pathway. LDL (low-density lipoprotein) is often referred to as "bad" cholesterol because high levels of LDL can lead to the buildup of cholesterol in the arteries, increasing the risk of cardiovascular diseases. HDL, on the other hand, acts protectively. It picks up excess cholesterol from the blood vessels, including cholesterol deposits in artery walls, and returns it to the liver. This helps prevent the accumulation of cholesterol in the arteries, reducing the risk of heart disease. VLDL (very low-density lipoprotein) and chylomicrons are also types of lipoproteins involved in lipid transport, but they are not typically emphasized as "good" or "bad" cholesterol. VLDL is involved in transporting triglycerides, while chylomicrons transport dietary fats. Their roles are more focused on delivering fats to tissues rather than cholesterol management.