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Klinisk Biokemi i Norden · 2 2017
Constituents of the plasma lipid profile (Figure 1)
A standard lipid profile includes measurements of
plasma or serum concentrations of:
• Total cholesterol
• Low-density lipoprotein (LDL) cholesterol
• High-density lipoprotein (HDL) cholesterol
• Triglycerides
Total cholesterol, HDL cholesterol, and triglycerides
are measured directly, while LDL cholesterol can either
be measured directly or calculated by the Friedewald
equation if triglycerides are <4.5mmol/L(<400mg/
dL): total cholesterol minus HDL cholesterol minus
triglycerides/2.2 (all in mmol/L; or minus triglyceri-
des/5 with values in mg/dL)
18
, with direct measure-
ment of LDL cholesterol at triglyceride concentrations
≥4.5mmol/L(400mg/dL). Traditionally, the Friedewald
equation has been applied to a fasting lipid profile;
however, calculated LDL cholesterol determined with
this equation at triglyceride concentrations <4.5mmol/
L(400mg/dL) is similar to LDL cholesterol measured
directly on both fasting and nonfasting lipid profiles
(Figure 2)
19,20
. These four measurements can, without
additional cost, be supplemented with:
• Remnant cholesterol
• NonHDL cholesterol
Remnant cholesterol (=triglyceride-rich lipoprotein
cholesterol) is calculated as total cholesterol minus
LDL cholesterol minus HDL cholesterol, using non-
0
2
4
6
8
10
Measured LDL cholesterol, mmol/L
0
2
4
6
8
10
Calculated LDL cholesterol, mmol/L
0
2
4
6
8
10
0
2
4
6
8
10
Calculated LDL cholesterol, mmol/L
-10
-5
0
5
10
0
2
4
6
8
10
(CalLDL-C + mesLDL-C)/2, mmol/L
-10
-5
0
5
10
MesLDL-C - calLDL-C, mmol/L
0
2
4
6
8
10
(CalLDL-C + mesLDL-C)/2, mmol/L
Nonfasting
Fasting
N= 5436
N= 470
R
2
= 0.84
MesLDL-C = 0.95 * calLDL-C + 0.29
R
2
= 0.87
MesLDL-C = 0.97 * calLDL-C + 0.20
Bias: -0.1 (95%CI: -0.9;0.6)
Bias: -0.1 (95%CI: -0.8;0.6)
Figure 2
0
2
4
6
8
10
Measured LD cholesterol, mmol/L
0
2
4
6
8
10
Calculated LDL cholesterol, mmol/L
0
2
4
6
8
10
0
2
4
6
8
10
Calculated LDL cholesterol, mmol/L
-10
-5
0
5
10
0
2
4
6
8
10
(CalLDL-C + mesLDL-C)/2, mmol/L
-10
-5
0
5
10
MesLDL-C - calLDL-C, mmol/L
0
2
4
6
8
10
(CalLDL-C + mesLDL-C)/2, mmol/L
Nonfasting
Fasting
N= 5436
N= 470
R
2
= 0.84
MesLDL-C = 0.95 * calLDL-C + 0.29
R
2
= 0.87
MesLDL-C = 0.97 * calLDL-C + 0.20
Bias: -0.1 (95%CI: -0.9;0.6)
Bias: -0.1 (95%CI: -0.8;0.6)
Figure 2
Figure 2. Comparison of calculated LDL cholesterol using the Friedewald equation with LDL cholesterol measured directly
using random nonfasting and fasting lipid profiles. Only lipid profiles with triglycerides <4.5 mmol/L (400 mg/dL) were incl -
ded, as LDL is typically measured using a direct LDL cholesterol assay when triglycerides are ≥4.5 mmol/L. Mes=measured.
Cal=calculated using the Friedewald equation (LDL cholesterol = total cholesterol minus HDL cholesterol minus triglyceri-
des/2.2; all values in mmol/L; if values are in mg/dL then use triglycerides/5). Figure designed by Prof B. G. Nordestgaard and
Dr. A. Langsted based on unpublished data from individuals participating in the Copenhagen City Heat Study 2001-2003
examination.
