1. What is the LDL Cholesterol Calculation?

The Friedewald equation estimates LDL cholesterol from total cholesterol, HDL cholesterol, and triglycerides. This calculation is commonly used when a direct LDL measurement isn't available.

2. How Does the Calculator Work?

The calculator uses the Friedewald equation:

Where:

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

Explanation: The equation estimates LDL 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. Monitoring LDL levels helps assess cardiovascular risk and guide treatment decisions.

4. Using the Calculator

Tips: Enter all values in mg/dL. The equation is valid when triglycerides are below 400 mg/dL. For higher TG levels, direct LDL measurement is recommended.

5. Frequently Asked Questions (FAQ)

Q1: Why divide triglycerides by 5?
A: This estimates VLDL cholesterol, as VLDL typically carries about 20% of triglycerides (hence 1/5 of TG = VLDL).

Q2: What are normal LDL values?
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 this calculation not accurate?
A: When triglycerides are >400 mg/dL, in non-fasting samples, or in certain conditions like type III hyperlipidemia.

Q4: How often should LDL be checked?
A: Adults should have a lipid panel every 4-6 years. Those with risk factors may need more frequent testing.

Q5: Are there better methods than this calculation?
A: Direct LDL measurement is more accurate but more expensive. Newer equations like Martin/Hopkins may be more precise at very low LDL levels.