1. What is the Friedewald Equation?

The Friedewald equation is a formula used to estimate LDL cholesterol (LDL-C) levels from measured total cholesterol, HDL cholesterol, and triglyceride levels. 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:

• \( LDL-C \) — 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-C Calculation

Details: Accurate LDL-C estimation is crucial for assessing cardiovascular risk, guiding lipid-lowering therapy, and monitoring treatment effectiveness in patients with dyslipidemia.

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 triglyceride levels 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, in non-fasting samples, or in patients with type III hyperlipoproteinemia.

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

Q3: How does this compare to direct LDL measurement?
A: Direct measurement is more accurate, especially when triglycerides are elevated, but the Friedewald equation provides a good estimate in most routine clinical situations.

Q4: Why divide triglycerides by 5?
A: This factor approximates the cholesterol content in very low-density lipoproteins (VLDL), which carry most triglycerides in the blood.

Q5: Are there updated versions of this equation?
A: Yes, newer equations like the Martin/Hopkins method have been developed to improve accuracy, particularly at low LDL and high triglyceride levels.