1. What is the LDL-C Formula?

The LDL-C formula calculates low-density lipoprotein cholesterol concentration using the Friedewald equation. This estimation is widely used in clinical practice when direct LDL measurement is not available.

2. How Does the Calculator Work?

The calculator uses the Friedewald equation:

Where:

• \( TC \) — Total cholesterol (mmol/L)
• \( HDL-C \) — HDL cholesterol (mmol/L)
• \( TG \) — Triglycerides (mmol/L)

Explanation: The formula estimates LDL cholesterol by subtracting HDL cholesterol and VLDL cholesterol (estimated as TG/2.2) from total cholesterol.

3. Importance of LDL-C Calculation

Details: LDL cholesterol is a major risk factor for cardiovascular disease. Accurate estimation helps in assessing cardiovascular risk and guiding lipid-lowering therapy decisions.

4. Using the Calculator

Tips: Enter all values in mmol/L. The formula is valid when triglycerides are below 4.5 mmol/L. For higher triglyceride levels, direct LDL measurement is recommended.

5. Frequently Asked Questions (FAQ)

Q1: When is the Friedewald equation not accurate?
A: The equation is less accurate when triglycerides exceed 4.5 mmol/L, in non-fasting samples, or in patients with certain dyslipidemias.

Q2: What are optimal LDL-C levels?
A: Generally, LDL-C below 2.6 mmol/L is desirable, below 1.8 mmol/L for high-risk patients, but targets should be individualized based on overall cardiovascular risk.

Q3: Should samples be fasting for this calculation?
A: Yes, fasting for 9-12 hours is recommended for accurate triglyceride measurement, which affects the LDL calculation.

Q4: Are there alternative equations for LDL estimation?
A: Yes, newer equations like the Martin/Hopkins method have been developed for improved accuracy, especially at low LDL and high triglyceride levels.

Q5: When should direct LDL measurement be used instead?
A: Direct measurement is preferred when triglycerides exceed 4.5 mmol/L, in non-fasting states, or when precise LDL quantification is clinically important.