My medical history includes a high triglyceride level over 400, and my doctor asked for a direct measurement of my LDL. Usually, the labs calculate the LDL by using a formula rather than measuring it directly. As Dr. Michael Eades says in his blog:

… Friedewald substituted triglycerides (TGL) divided by 5 for VLDL in the above equations, giving us the so-called Friedewald equation for calculating LDL.

LDL = Total cholesterol – HDL – TGL/5

And this is how it is still done in labs all over the world 27 years after Friedewald’s paper. If you’ve had a lab report showing an LDL figure, I can guarantee it was calculated by the Freidewald equation and not measured directly.

It has long been recognized that if the triglycerides are over 400, the calculation does not work. So you have to measure the level directly. In that same blog post, Dr. Eades explains his experience that LDL calculations are inaccurate when the triglycerides are low as well. I have linked two articles Dr. Eades identifies as supporting that position in our new LDL Research Page.

Many studies show marked improvement in patients HDL, triglycerides and glucose levels with low carb diets. Often, the low carb dieter has a rise in total cholesterol and LDL. Researchers are not concerned with the higher total cholesterol number, but the LDL level increase does concern them. But most studies use the Friedewald calculation that may not give an accurate picture of the true LDL level.

If my LDL gets too high, I’ll be certain to ask for a direct measurement of it, rather than a calculation. The extra cost for the test is probably cheaper than taking statins.

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