Laboratory & Electrolytes

LDL Cholesterol (Friedewald)

Calculate LDL cholesterol using the Friedewald equation from a standard lipid panel.

When to use: Use Friedewald LDL to interpret routine fasting lipid panels when triglycerides are below 400 mg/dL. LDL is the primary atherogenic lipoprotein and the key treatment target for cardiovascular risk reduction. For non-fasting samples or when TG ≥400 mg/dL (diabetes, hypothyroidism, nephrotic syndrome), request a direct LDL measurement or use the Martin-Hopkins equation, which is more accurate at high TG levels.

Calculator

Total Cholesterol(mg/dL)

HDL Cholesterol(mg/dL)

Triglycerides(mg/dL)Formula is invalid when TG ≥400 mg/dL — use direct LDL measurement instead

Fill in all fields to see the result

Formula

LDL = Total Cholesterol − HDL − (Triglycerides / 5) Valid only when TG <400 mg/dL (Friedewald, 1972) <100: Optimal | 100–129: Near optimal | 130–159: Borderline high | 160–189: High | ≥190: Very high

Key Points for NEET PG

Friedewald equation: LDL = TC − HDL − TG/5; TG/5 estimates VLDL-C. Invalid when TG ≥400 mg/dL.
ACC/AHA 2018 guidelines: high-intensity statin for LDL ≥190, for ASCVD, and for DM with 10-yr risk ≥7.5%.
LDL target in high-risk patients: <70 mg/dL (established CVD, post-MI); in very-high-risk: <55 mg/dL (ESC 2019).
Non-HDL cholesterol (TC − HDL) is a better target than LDL when TG is elevated — includes all atherogenic particles.
Familial hypercholesterolaemia: LDL >190 + family history or tendon xanthomas — autosomal dominant, LDLR/ApoB/PCSK9 mutations.

References

Friedewald WT, Levy RI, Fredrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge · Clin Chem (1972)

Grundy SM et al. 2018 AHA/ACC Guideline on the Management of Blood Cholesterol · J Am Coll Cardiol (2019)

For educational purposes only. Not for clinical decision-making without professional oversight.