1. What is the Friedewald Equation?

The Friedewald equation estimates LDL cholesterol from total cholesterol, HDL cholesterol, and triglyceride levels. It is a widely used method for LDL calculation in clinical practice when direct measurement is not available.

2. How Does the Calculator Work?

The calculator uses the Friedewald equation:

Where:

• \( TC \) — Total cholesterol (mg/dL)
• \( HDL-C \) — HDL cholesterol (mg/dL)
• \( TG \) — Triglycerides (mg/dL)

Explanation: The equation estimates LDL cholesterol by subtracting HDL cholesterol and VLDL cholesterol (estimated as TG/5) from total cholesterol.

3. Importance of LDL Calculation

Details: LDL cholesterol is a major risk factor for cardiovascular disease. Accurate estimation helps in assessing cardiovascular risk and guiding lipid-lowering therapy decisions.

4. Using the Calculator

Tips: Enter total cholesterol, HDL cholesterol, and triglycerides in mg/dL. All values must be valid (greater than 0). Note: This equation is not valid when triglycerides exceed 400 mg/dL.

5. Frequently Asked Questions (FAQ)

Q1: When should the Friedewald equation not be used?
A: The equation should not be used when triglyceride levels exceed 400 mg/dL, as it becomes less accurate in these cases.

Q2: What are the limitations of the Friedewald equation?
A: It underestimates LDL cholesterol at low LDL levels and overestimates at high triglyceride levels. Direct LDL measurement is preferred in these scenarios.

Q3: What are optimal LDL cholesterol levels?
A: Optimal LDL cholesterol is generally below 100 mg/dL, though target levels may vary based on individual cardiovascular risk factors.

Q4: How often should LDL be measured?
A: Frequency depends on individual risk factors, but generally every 4-6 years for adults without risk factors, and more frequently for those with elevated risk.

Q5: Are fasting samples required for accurate results?
A: Yes, a 9-12 hour fasting sample is recommended for accurate triglyceride measurement, which affects the LDL calculation.