1. What is the Friedewald Formula?

The Friedewald formula is a widely used equation to estimate LDL cholesterol levels when a direct measurement is not available. It calculates LDL based on total cholesterol, HDL cholesterol, and triglyceride levels.

2. How Does the Calculator Work?

The calculator uses the Friedewald formula:

Where:

• Total Cholesterol — Measured in mg/dL
• HDL — High-density lipoprotein cholesterol in mg/dL
• Triglycerides — Measured in mg/dL

Explanation: The formula estimates LDL by subtracting HDL and VLDL (estimated as triglycerides/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 all values in mg/dL. The formula is most accurate when triglycerides are below 400 mg/dL. For higher levels, direct LDL measurement is recommended.

5. Frequently Asked Questions (FAQ)

Q1: Why divide triglycerides by 5?
A: This estimates VLDL cholesterol, as VLDL typically carries about 20% of triglycerides by weight (hence 1/5).

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

Q3: When is the Friedewald formula inaccurate?
A: When triglycerides >400 mg/dL, in non-fasting samples, or in certain conditions like type III hyperlipidemia.

Q4: Are there alternative formulas?
A: Yes, the Martin/Hopkins equation may be more accurate for very low LDL or high triglyceride levels.

Q5: Should this be used for treatment decisions?
A: While useful for screening, treatment decisions should be based on direct LDL measurements when available.