1. What is the Friedewald Formula?

The Friedewald formula is a widely used equation to estimate LDL cholesterol levels without requiring direct measurement. It provides a calculated LDL value based on total cholesterol, HDL cholesterol, and triglyceride measurements.

2. How Does the Calculator Work?

The calculator uses the Friedewald formula:

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 formula estimates LDL cholesterol by subtracting HDL and VLDL (estimated as TG/5) from total cholesterol.

3. Importance of LDL Calculation

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

4. Using the Calculator

Tips: Enter total cholesterol, HDL cholesterol, and triglycerides in mg/dL. All values must be valid (greater than 0). Note that the formula is less accurate when triglyceride levels exceed 400 mg/dL.

5. Frequently Asked Questions (FAQ)

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

Q2: What are the limitations of calculated LDL?
A: Calculated LDL may underestimate true LDL levels in hypertriglyceridemia and doesn't account for LDL subclass patterns that may affect cardiovascular risk.

Q3: When should direct LDL measurement be used instead?
A: Direct measurement is recommended when triglycerides exceed 400 mg/dL, in patients with diabetes, or when more precise LDL quantification is needed.

Q4: Are there alternative formulas for LDL calculation?
A: Yes, other formulas like the Martin/Hopkins equation or Sampson equation have been developed to improve accuracy, especially at very low or high triglyceride levels.

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