1. What is the Friedewald Equation?

The Friedewald equation is a formula used to estimate LDL cholesterol levels from measurements of total cholesterol, HDL cholesterol, and triglycerides. 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 (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 VLDL cholesterol (estimated as TG/5) from total cholesterol.

3. Importance of LDL Calculation

Details: Accurate LDL cholesterol estimation is crucial for assessing cardiovascular risk, guiding lipid-lowering therapy, and monitoring treatment effectiveness in patients with dyslipidemia.

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 triglyceride levels 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 certain lipid disorders.

Q2: What are the limitations of the Friedewald equation?
A: It may underestimate LDL levels in patients with low LDL and high triglycerides, and overestimate in those with very low triglyceride levels.

Q3: Are there alternative methods for LDL estimation?
A: Yes, direct LDL measurement and the Martin/Hopkins equation are alternatives, especially when triglycerides are elevated.

Q4: What are optimal LDL cholesterol levels?
A: Generally, LDL below 100 mg/dL is optimal, below 70 mg/dL for high-risk patients, and below 55 mg/dL for very high-risk patients.

Q5: How often should LDL be measured?
A: Frequency depends on individual risk factors, but generally every 4-12 weeks when initiating therapy and every 3-12 months for monitoring.