1. What is LDL Cholesterol?

LDL (low-density lipoprotein) cholesterol, often called "bad cholesterol," contributes to fatty buildups in arteries (atherosclerosis). The Friedewald equation estimates LDL when a direct measurement isn't available.

2. How Does the Calculator Work?

The calculator uses the Friedewald equation:

Where:

• \( TC \) — Total cholesterol (mg/dL)
• \( HDL \) — HDL cholesterol (mg/dL)
• \( TG \) — Triglycerides (mg/dL)

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

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.

4. Using the Calculator

Tips: Enter all values in mg/dL. For accurate results, blood should be drawn after 9-12 hours of fasting. The equation is not valid if triglycerides exceed 400 mg/dL.

5. Frequently Asked Questions (FAQ)

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

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

Q3: When is direct LDL measurement needed?
A: When triglycerides >400 mg/dL, in non-fasting samples, or with certain conditions like diabetes or very low LDL.

Q4: Can this be used for children?
A: The equation is validated for adults. Pediatric LDL should be interpreted using age-specific percentiles.

Q5: How often should LDL be checked?
A: Adults 20+ should have lipids checked every 4-6 years; more often if risk factors exist or on lipid-lowering therapy.