1. What is the Friedewald Formula?

The Friedewald formula is a widely used method for estimating LDL cholesterol levels without requiring direct measurement. It calculates LDL-C based on total cholesterol, HDL cholesterol, and triglyceride levels measured in mmol/L.

2. How Does the Calculator Work?

The calculator uses the Friedewald formula:

Where:

• \( TC \) — Total cholesterol (mmol/L)
• \( HDL-C \) — HDL cholesterol (mmol/L)
• \( TG \) — Triglycerides (mmol/L)

Explanation: The formula estimates LDL cholesterol by subtracting HDL cholesterol and VLDL cholesterol (estimated as TG/2.2) 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 treatment decisions for cholesterol management.

4. Using the Calculator

Tips: Enter total cholesterol, HDL cholesterol, and triglycerides in mmol/L. All values must be valid (positive numbers). Note: This formula is not accurate when triglyceride levels exceed 4.5 mmol/L.

5. Frequently Asked Questions (FAQ)

Q1: When is the Friedewald formula not appropriate?
A: The formula should not be used when triglyceride levels are above 4.5 mmol/L, in non-fasting samples, or in patients with certain metabolic disorders.

Q2: What are optimal LDL cholesterol levels?
A: Optimal LDL levels are generally below 2.6 mmol/L, though target levels may vary based on individual cardiovascular risk factors.

Q3: How does this differ from the mg/dL version?
A: The mmol/L version uses a divisor of 2.2 instead of 5 used in the mg/dL version to estimate VLDL cholesterol from triglycerides.

Q4: Are there limitations to this formula?
A: Yes, it becomes less accurate at very high triglyceride levels and may underestimate LDL in certain populations. Direct LDL measurement is preferred in these cases.

Q5: Should fasting be required for this calculation?
A: Yes, for accurate results, blood samples should be taken after a 9-12 hour fast as triglyceride levels are significantly affected by recent food intake.