1. What is the Friedewald Equation?

The Friedewald equation is a formula used to estimate LDL cholesterol levels from total cholesterol, HDL cholesterol, and triglyceride measurements. It provides a cost-effective alternative to direct LDL measurement in routine clinical practice.

2. How Does the Calculator Work?

The calculator uses the Friedewald equation:

Where:

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

Explanation: The equation estimates LDL cholesterol by subtracting HDL cholesterol and one-fifth of triglycerides 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 is the Friedewald equation not accurate?
A: The equation becomes inaccurate when triglycerides exceed 400 mg/dL, in non-fasting samples, or in patients with dysbetalipoproteinemia.

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

Q3: Should samples be fasting?
A: Yes, for accurate results, blood should be drawn after a 9-12 hour fast to minimize triglyceride variability.

Q4: Are there alternative equations?
A: Yes, the Martin-Hopkins equation and Sampson equation are alternative methods that may be more accurate in certain populations.

Q5: When should direct LDL measurement be used?
A: Direct measurement is recommended when triglycerides >400 mg/dL or when more precise LDL quantification is needed.