1. What is the Friedewald Equation?

The Friedewald equation is a formula used to estimate LDL cholesterol 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 (mmol/L)
• \( TC \) — Total cholesterol (mmol/L)
• \( HDL-C \) — High-density lipoprotein cholesterol (mmol/L)
• \( TG \) — Triglycerides (mmol/L)

Explanation: The equation 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 lipid-lowering therapy decisions.

4. Using the Calculator

Tips: Enter all values in mmol/L. Ensure triglyceride levels are below 4.5 mmol/L for accurate results. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: When is the Friedewald equation not accurate?
A: The equation is less accurate when triglyceride levels exceed 4.5 mmol/L, in non-fasting samples, or in certain medical conditions like diabetes.

Q2: What are normal LDL cholesterol levels?
A: Optimal LDL is <2.6 mmol/L, near optimal is 2.6-3.3 mmol/L, borderline high is 3.4-4.1 mmol/L, high is 4.1-4.9 mmol/L, and very high is ≥4.9 mmol/L.

Q3: Should I be fasting for this test?
A: Yes, lipid profiles should be measured after a 9-12 hour fast for most accurate results, especially for triglyceride measurement.

Q4: Are there alternative methods for LDL measurement?
A: Yes, direct LDL measurement is available and recommended when triglycerides are elevated (>4.5 mmol/L) or when more precise measurement is needed.

Q5: How often should cholesterol be checked?
A: Adults should have cholesterol checked every 4-6 years. More frequent testing may be needed for those with risk factors or on lipid-lowering therapy.