1. What is the Friedewald Equation?

The Friedewald equation is a formula used to estimate LDL cholesterol levels from total cholesterol, HDL cholesterol, and triglyceride measurements. It provides a cost-effective alternative to direct LDL measurement in most clinical situations.

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 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 total cholesterol, HDL cholesterol, and triglycerides in mg/dL. All values must be valid (greater than 0). Note: This equation is not valid when triglycerides 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 dysbetalipoproteinemia.

Q2: What are the limitations of the Friedewald equation?
A: It tends to underestimate LDL-C at lower LDL levels and overestimate at higher levels. Direct LDL measurement is preferred in certain clinical scenarios.

Q3: Are there alternative equations for LDL estimation?
A: Yes, the Martin-Hopkins equation and Sampson equation are more recent alternatives that may provide better accuracy, especially at low LDL levels.

Q4: How often should LDL be measured?
A: Frequency depends on individual risk factors, but generally every 4-6 weeks after starting treatment and every 6-12 months for monitoring.

Q5: What are optimal LDL levels?
A: Optimal levels vary based on cardiovascular risk, but generally <100 mg/dL is desirable, with <70 mg/dL recommended for high-risk patients.