Bioquímica Clínica 02/03

Summary

This lecture focuses on lipids, dyslipidemia, and the importance of lipid profiles in diagnosing cardiovascular risks. It explains lipid functions, such as energy storage and hormone production, and describes how lipids are transported in the bloodstream by lipoproteins. The video also highlights methods for measuring lipid levels, including enzymatic colorimetric assays, and provides insights into reference values and therapeutic targets for cholesterol and triglycerides. Additionally, it discusses the 2017 consensus that fasting is no longer necessary for lipid tests and emphasizes the personalized approach in managing lipid levels based on cardiovascular risk.

Takeaways

• 😀 Lipids are organic compounds that are insoluble in water and play crucial roles in energy storage, cell structure, and hormone production.
• 😀 Cholesterol and triglycerides are the main lipids in the body, with cholesterol primarily produced by the liver and triglycerides influenced by diet.
• 😀 A lipid profile is a laboratory test that measures total cholesterol, HDL, LDL, and triglycerides, helping diagnose lipid disorders like dyslipidemia.
• 😀 LDL (low-density lipoprotein) is known as 'bad cholesterol' because high levels increase cardiovascular risk, while HDL (high-density lipoprotein) is the 'good cholesterol' that protects against this risk.
• 😀 Lipids cannot dissolve in water, so they are transported in the blood by lipoproteins, which are proteins that carry lipids through the bloodstream.
• 😀 VLDL (Very Low-Density Lipoprotein) carries triglycerides and cholesterol, LDL carries cholesterol, and HDL removes excess cholesterol from the blood.
• 😀 Modern lipid tests use enzymatic colorimetric methods, with most labs calculating LDL instead of directly measuring it due to cost constraints.
• 😀 The 2017 Brazilian consensus changed the interpretation of LDL and non-HDL, focusing on cardiovascular risk rather than fixed reference values.
• 😀 A low-risk patient should aim for an LDL level below 130 mg/dL, while a high-risk patient should aim for an LDL below 50 mg/dL.
• 😀 Triglycerides are measured as part of the lipid profile, with values below 150 mg/dL considered desirable and levels above 500 mg/dL categorized as very high.
• 😀 The method used for lipid analysis is typically an enzymatic reaction, and the results can help diagnose cardiovascular diseases, including atherosclerosis, caused by high levels of LDL and total cholesterol.

Q & A

What are lipids, and why are they important in the human body?

Lipids are organic compounds that are oily or fatty in nature. They are important for the body as they serve as structural components of cell membranes, precursors to hormones, and energy reserves, especially in the form of triglycerides.

What is the role of cholesterol in the body?

Cholesterol plays a key role in the production of hormones, bile salts, and vitamin D. It is also essential for maintaining the structure and function of cell membranes.

What is the difference between HDL and LDL cholesterol?

HDL (High-Density Lipoprotein) is known as 'good cholesterol' because it helps remove excess cholesterol from the bloodstream, reducing the risk of heart disease. LDL (Low-Density Lipoprotein), known as 'bad cholesterol,' carries cholesterol to tissues, and high levels can lead to the buildup of plaques in arteries, increasing the risk of cardiovascular disease.

What is the lipid profile, and why is it important?

The lipid profile is a blood test that measures the levels of different types of cholesterol (total cholesterol, HDL, LDL) and triglycerides. It is crucial for assessing the risk of cardiovascular diseases, such as heart attacks and strokes.

What are triglycerides, and what role do they play in the body?

Triglycerides are a type of fat stored in the body. They serve as a secondary source of energy when glucose is unavailable. However, excessive levels of triglycerides can contribute to cardiovascular problems.

How is LDL cholesterol calculated in a lipid profile test?

LDL cholesterol is typically calculated using the Friedewald formula: LDL = Total cholesterol - HDL - (Triglycerides / 5). This formula works well when triglyceride levels are below 400 mg/dL. When triglycerides exceed 400 mg/dL, a different calculation method is used.

Is fasting required before a lipid profile test?

No, fasting is no longer necessary before a lipid profile test. Recent guidelines, including those from a 2017 Brazilian consensus, state that a 12-hour fast is not required for accurate results.

What is the significance of VLDL in lipid testing?

VLDL (Very Low-Density Lipoprotein) is a lipoprotein that primarily carries triglycerides in the blood. It is important to monitor VLDL levels because high amounts can contribute to the development of atherosclerosis and increase the risk of cardiovascular disease.

What are the target values for lipids in adults over 20 years old?

For adults over 20, the target values for lipids are: Total cholesterol < 190 mg/dL, HDL > 40 mg/dL, LDL < 130 mg/dL, and Triglycerides < 150 mg/dL. These values are based on a general cardiovascular risk assessment.

How are lipid levels interpreted in relation to cardiovascular risk?

Lipid levels, particularly LDL and non-HDL cholesterol, are interpreted based on the patient's cardiovascular risk. For example, an LDL level below 130 mg/dL is considered low risk, while a level below 50 mg/dL is high risk. The overall risk is assessed by considering factors like family history, age, and lifestyle.