This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

LDL cholesterol measurement

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

The Friedewald Equation

  • the ultracentrifugal measurement of LDL is time consuming and expensive and requires specialist equipment. For this reason, LDL-cholesterol is most commonly estimated from quantitative measurements of total and HDL-cholesterol and plasma triglycerides (TG) using the empirical relationship of Friedewald et al.(1972).
    • [LDL-chol] = [Total chol] - [HDL-chol] - ([TG]/2.2) where all concentrations are given in mmol/L (note that if calculated using all concentrations in mg/dL then the equation is [LDL-chol] = [Total chol] - [HDL-chol] - ([TG]/5))
    • the quotient ([TG]/5) is used as an estimate of VLDL-cholesterol concentration. It assumes, first, that virtually all of the plasma TG is carried on VLDL, and second, that the TG:cholesterol ratio of VLDL is constant at about 5:1 (Friedewald et al. 1972). Neither assumption is strictly true.
  • Limitations of the Friedewald equation
    • The Friedewald equation should not be used under the following circumstances:
      • when chylomicrons are present
      • when plasma triglyceride concentration exceeds 400 mg/dL (4.52 mmol/L)
      • in patients with dysbetalipoproteinemia (type III hyperlipoproteinemia

Related pages

Create an account to add page annotations

Annotations allow you to add information to this page that would be handy to have on hand during a consultation. E.g. a website or number. This information will always show when you visit this page.