LDL was previously calculated from triglyceride, cholesterol and HDL cholesterol using the Friedewald formula.
As from 22nd of February 2024, LDL is calculated using the Sampson equation.
Friedewald knew that with increasing triglyceride levels, the calculated LDL-C was progressively falsely lower when compared with the gold standard technique and therefore Friedewald stated LDL-C should not be calculated when triglycerides are > 4.5 mmol/L. With much lower LDL-C levels seen in the statin era, an improved calculation was required, hence the Sampson equation.
Comparing both equations with the gold standard ultracentrifugation method, Sampson LDL-C offers similar or better accuracy than Friedewald LDL-C at any triglyceride level. Sampson LDL-C can also be calculated up to a triglyceride level of 9 mmol/L.
Friedewald: LDL-C = TC – HDL-C – Triglycerides/2.2
Sampson: LDL-C = (TC×40.791 − HDL-C×39.825 − (TG×10.35 + TG× non-HDL-C×1.6 − TG2×0.467) − 9.44) / 38.67
The calculation for the Sampson equation is complicated but Friedewald LDL-C can be (easily) calculated from the available lipid results if required.
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