1. What is the Friedewald Equation?

The Friedewald equation is a formula used to estimate LDL cholesterol (LDL-C) levels from measurements of total cholesterol, HDL cholesterol, and triglycerides. It provides a practical alternative to direct measurement when resources are limited.

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-C Calculation

Details: LDL cholesterol is a major risk factor for cardiovascular disease. Accurate estimation helps assess cardiovascular risk and guide treatment decisions, particularly lipid-lowering therapy.

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 less accurate when triglyceride levels exceed 400 mg/dL.

5. Frequently Asked Questions (FAQ)

Q1: When is the Friedewald equation not accurate?
A: The equation is less reliable when triglyceride levels are above 400 mg/dL, in non-fasting samples, or in patients with certain metabolic disorders.

Q2: What are optimal LDL-C levels?
A: Optimal LDL-C is generally below 100 mg/dL, though targets may be lower for high-risk patients (e.g., below 70 mg/dL).

Q3: Should samples be fasting for this calculation?
A: Yes, for accurate results, blood should be drawn after a 9-12 hour fast, as triglyceride levels are affected by recent food intake.

Q4: Are there alternatives to the Friedewald equation?
A: Yes, direct LDL-C measurement or the Martin/Hopkins equation may be used, especially when triglycerides are elevated.

Q5: Can this calculator be used for children?
A: The equation is validated primarily for adults. Pediatric lipid assessment should use age-specific percentiles and direct measurement when possible.