1. What is the Friedewald Equation?

The Friedewald equation is a formula used to estimate LDL cholesterol (LDL-C) levels from measurements of total cholesterol, HDL cholesterol, and triglycerides. It provides a practical alternative to direct LDL measurement when resources are limited.

2. How Does the Calculator Work?

The calculator uses the Friedewald equation:

Where:

• \( TC \) — Total cholesterol (mmol/L)
• \( HDL-C \) — HDL cholesterol (mmol/L)
• \( TG \) — Triglycerides (mmol/L)

Explanation: The equation estimates LDL cholesterol by subtracting HDL cholesterol and VLDL cholesterol (estimated as TG/2.2) from total cholesterol.

3. Importance of LDL-C Calculation

Details: LDL cholesterol is a major risk factor for cardiovascular disease. Accurate estimation helps in assessing cardiovascular risk and guiding treatment decisions for cholesterol management.

4. Using the Calculator

Tips: Enter total cholesterol, HDL cholesterol, and triglycerides in mmol/L. All values must be valid positive numbers. Note: This equation is not valid when triglyceride levels exceed 4.5 mmol/L.

5. Frequently Asked Questions (FAQ)

Q1: When should I not use the Friedewald equation?
A: The equation should not be used when triglyceride levels exceed 4.5 mmol/L, in non-fasting samples, or in patients with type III hyperlipoproteinemia.

Q2: What are optimal LDL cholesterol levels?
A: Optimal LDL levels are generally below 2.6 mmol/L, but targets may vary based on individual cardiovascular risk factors.

Q3: How accurate is the Friedewald equation compared to direct measurement?
A: The equation provides a good estimate in most cases but may underestimate LDL-C at lower levels and overestimate at higher levels compared to direct measurement.

Q4: Are there alternative equations for LDL estimation?
A: Yes, newer equations like the Martin/Hopkins method may provide more accurate estimates, especially at very low LDL or high triglyceride levels.

Q5: Should fasting be required for this calculation?
A: Yes, for accurate results, blood should be drawn after a 9-12 hour fast as triglyceride levels are significantly affected by recent food intake.