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Test & Collection Guide

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PLEASE NOTE: Recent changes have been made to this Test


 Recent changes for Cholesterol, Low Density Lipoprotein

Recent changes for Cholesterol, Low Density Lipoprotein

Date
Field
Changed From
Changed To
29th February 2024
Notes

 

LDL is not measured directly, but is calculated using the Friedwald formula:

(LDLC) = (total CHOL) - (HDLC) - (TG/2.2)

This formula cannot be used where TG > 4.5 mmol/L

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/0.948−HDL-C/0.971−(TG/8.56+TG × non-HDL-C/2140 −TG2/16100)−9.44


The calculation for the Sampson equation is complicated but Friedewald LDL-C can be (easily) calculated from the available lipid results if required.
 

 

Cholesterol, Low Density Lipoprotein

Alternate names:
LDL, LDLC
Laboratory:
Biochemistry
Specimen types:
Serum
Container types:
Serum tube with gelSerum tube with gel
Collection Instructions:

Patient should be fasting for 12 hours

Notes:

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.
 

 

Frequency:
Daily
Result Turnaround Time:
4 hours
Reference Interval:

Desirable: < 3.0 mmol/L

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