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April 1991

Calculation of Low-Density Lipoprotein Cholesterol

Author Affiliations

Québec City, Québec

Arch Intern Med. 1991;151(4):810. doi:10.1001/archinte.1991.00400040140033

To the Editor.—  In their article, Leighton et al1 used Système International (SI) units to report their results with the corresponding traditional units in brackets. However, the equation they included in their "Methods" section for the calculation of low-density lipoprotein cholesterol (LDL-C) can be applied only with the latter units.2 The correct equation to use with SI units is: LDL-C = Total Cholesterol— (HDL-C + 0.38 × Triglycerides). This error is not uncommon in the American literature.3-5 Authors should be reminded that familiar equations used with traditional units must be adapted before utilization with SI units. By the way, I would like to mention that two recent articles6,7 demonstrated that the original Friedewald equation8 generally gives a more accurate estimation of LDL-C than the modified version.2