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 provides a practical method for LDL-C estimation without requiring direct measurement, which is more complex and costly.

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-C by subtracting HDL-C and VLDL-C (estimated as TG/5) 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 managing 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 TG > 400 mg/dL.

5. Frequently Asked Questions (FAQ)

Q1: Why use the Friedewald equation?
A: It provides a simple, cost-effective method to estimate LDL-C without direct measurement, making it widely used in clinical practice.

Q2: What are normal LDL-C 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: When should lipid levels be measured?
A: Fasting sample (9-12 hours) is ideal for accurate triglyceride measurement, though non-fasting samples can be used for total and HDL cholesterol.

Q4: Are there limitations to this equation?
A: Less accurate when triglycerides >400 mg/dL, in type III hyperlipoproteinemia, or with very low LDL-C levels. Direct measurement is preferred in these cases.

Q5: Should this be used for everyone?
A: While useful for most patients, direct LDL-C measurement may be needed for those with hypertriglyceridemia or other special circumstances.