1. What is the Friedewald Equation?

The Friedewald equation estimates LDL cholesterol (LDL-C) from total cholesterol (TC), HDL cholesterol (HDL-C), and triglycerides (TG). It's a widely used method for calculating LDL when direct measurement isn't 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 and VLDL (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 assess cardiovascular risk and guide treatment 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 TG > 400 mg/dL.

5. Frequently Asked Questions (FAQ)

Q1: When is the Friedewald equation not accurate?
A: The equation becomes less accurate when triglycerides exceed 400 mg/dL, in non-fasting samples, or in certain medical conditions.

Q2: What are optimal LDL levels?
A: Optimal LDL is generally <100 mg/dL, though targets vary based on individual cardiovascular risk factors.

Q3: How should blood be drawn for accurate results?
A: A 9-12 hour fasting sample is recommended for most accurate lipid panel results.

Q4: Are there alternative methods for LDL calculation?
A: Yes, direct LDL measurement or the Martin/Hopkins method may be used when triglycerides are elevated.

Q5: Why divide triglycerides by 5?
A: This estimates VLDL cholesterol, as VLDL typically carries about 20% of triglyceride mass.