1. What is the Friedewald Equation?

The Friedewald equation is a formula used to estimate LDL cholesterol levels from a standard lipid panel without requiring direct measurement. It's widely used in clinical practice when direct LDL measurement isn't available.

2. How Does the Calculator Work?

The calculator uses the Friedewald equation:

Where:

• \( LDL \) — Low-density lipoprotein cholesterol (mg/dL)
• \( TC \) — Total cholesterol (mg/dL)
• \( HDL \) — High-density lipoprotein cholesterol (mg/dL)
• \( TG \) — Triglycerides (mg/dL)

Explanation: The equation estimates LDL 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 guide treatment decisions and assess cardiovascular risk.

4. Using the Calculator

Tips: Enter all values in mg/dL from a fasting lipid panel. The equation is most accurate when triglycerides are below 400 mg/dL.

5. Frequently Asked Questions (FAQ)

Q1: When is the Friedewald equation not accurate?
A: It's less accurate when triglycerides are >400 mg/dL, in non-fasting samples, or in certain conditions like diabetes or hypertriglyceridemia.

Q2: What are normal LDL values?
A: Optimal is <100 mg/dL, near optimal is 100-129 mg/dL, borderline high is 130-159 mg/dL, high is 160-189 mg/dL, and very high is ≥190 mg/dL.

Q3: Should this be used for patients with high triglycerides?
A: For TG >400 mg/dL, direct LDL measurement is recommended instead of the Friedewald calculation.

Q4: Are there newer equations than Friedewald?
A: Yes, the Martin/Hopkins equation may be more accurate in some cases, especially with low LDL or high TG.

Q5: Why divide triglycerides by 5?
A: This estimates VLDL cholesterol, assuming a fixed ratio between triglycerides and cholesterol in VLDL particles.