Background:
The calculation of serum low-density lipoprotein cholesterol (LDL-C) by the Friedewald formula does not accounted for the cholesterol associated with lipoprotein(a) [Lp(a)]. So we analyzed the effect of serum lipoprotein(a) on estimation of
low-density lipoprotein cholesterol by the Friedewald formula.
Methods:
To quantify the contribution of Lp(a) cholesterol to total serum cholesterol, we measured the concentration of the Lp(a) by an ELISA and the concentration of other serum lipids and the lipoproteins by the standard assays, and the LDL
cholesterol
estimated by the Fridewald formula and the Dahlen's modification of the Friedewald formula in 244 patients who had less than 400 mg/mL of triglyderide.
Results:
In measuring serum high-density lipoprotein we found that manganese chloride precipitated 100% of all Lp(a) in 11 random patients. When serum Lp(a) concentration were less than 30 mg/dL, between 31 and 60 mg/dL, and more than 61 mg/dL, the
uncorrected serum LDL-C was overestimated by a mean of 3.1% (n=145), 11.8% (n=63), and 21.2% (n=36), respectively. Serum Lp(a) concentrations were positively correlated with percentage overestimation (r=0.876, p<0.001) but were not correlated
with
either corrected or uncorrected serum LDL-C (r=0.106, p<0.001)
Conclusions:
We conclude that the Friedewald formula showed be take into account of the contribution of Lp(a) cholesterol to total serum cholesterol.
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