1. What is LDL Cholesterol?

LDL (low-density lipoprotein) cholesterol, often called "bad" cholesterol, is a type of cholesterol that can build up in artery walls, increasing risk of heart disease and stroke. The Friedewald formula provides an estimate of LDL cholesterol without requiring direct measurement.

2. How Does the Calculator Work?

The calculator uses the Friedewald formula:

Where:

• \( LDL \) — Low-density lipoprotein cholesterol (mg/dL)
• \( TC \) — Total cholesterol (mg/dL)
• \( HDL \) — High-density lipoprotein cholesterol (mg/dL)
• \( TG \) — Triglycerides (mg/dL)

Note: This formula is valid only when triglycerides are below 400 mg/dL. For higher values, direct LDL measurement is needed.

3. Importance of LDL Calculation

Details: LDL cholesterol is a major risk factor for cardiovascular disease. Monitoring LDL helps assess cardiovascular risk and guide treatment decisions like statin therapy.

4. Using the Calculator

Tips: Enter all values in mg/dL from a fasting lipid panel. Values must be positive numbers. Triglycerides should be less than 400 mg/dL for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: Why divide triglycerides by 5?
A: This approximates the cholesterol content in very-low-density lipoprotein (VLDL) particles, which carry most triglycerides in fasting blood.

Q2: What are normal LDL values?
A: Optimal is <100 mg/dL, near optimal 100-129 mg/dL, borderline high 130-159 mg/dL, high 160-189 mg/dL, very high ≥190 mg/dL.

Q3: When is this formula inaccurate?
A: When triglycerides ≥400 mg/dL, in non-fasting samples, or with certain conditions like type III hyperlipidemia.

Q4: Are there newer calculation methods?
A: Yes, the Martin/Hopkins method adjusts the TG/VLDL ratio dynamically, but Friedewald remains widely used.

Q5: How often should LDL be checked?
A: Adults should have lipid panels every 4-6 years; more often if risk factors exist or treatment is initiated.