Will the real LDL please stand up? 26. April 2009 William Davis (13) The results of the latest Heart Scan Blog poll are in.The question: How has your LDL been measured? The 187 responses broke down as:I have only had a conventional calculated value 108 (57%)NMR LDL particle number 35 (18%)Apoprotein B 21 (11%)Direct LDL cholesterol 21 (11%)Non-HDL cholesterol 8 (4%)I don't know what you're talking about 23 (12%)Remember the TV game show, To Tell the Truth? Celebrities would have to guess which of three guests represented the real person, such as the notorious con man, Frank Abagnale, Jr., or Mad Magazine publisher, William M. Gaines (who stumped celebrity Kitty Carlisle, heard to exclaim, "I never figured it was him. I mean look at the way he's dressed. I was looking for someone who ran a very successful magazine, so I thought it couldn't be him!")The celebrities playing the game were permitted to ask the three guests a series of questions, hoping to discern who was the real person vs. the two impostors. At the end, each celebrity had to guess who was truly the person of interest. "Will the real Frank Abagnale, Jr. please stand up!" If we were to act as the celebrities in our LDL game, we quickly discover some telling facts:--Conventional LDL cholesterol (the only value 57% of our poll respondents have had) is calculated, not measured. LDL is calculated using the 40-year old Friedewald calculation. --Directly measured LDL cholesterol (the value 11% of respondents had) is just that: directly measured. It eliminates some of the uncertainties of calculated LDL. --Apoprotein B-Every LDL and VLDL particle produced by the liver contains one apoprotein B molecule. ApoB therefore provides a crude particle count measure of LDL and VLDL particles. Of course, it includes VLDL and is not completely the same as just an LDL measure. Some lipid authorities Like Dr. Peter Kwiterovich have advocated that apoB replace calculated LDL, and that calculated LDL essentially be discarded.--Non-HDL cholesterol--I mention this more for completeness. Hardly anybody uses this crude value in practice--Indeed, only 4% of our poll respondents had this measure/calculation. Non-HDL is simply total cholesterol minus HDL cholesterol = Non-HDL cholesterol. It is thus a combination of cholesterol in LDL and VLDL (triglycerides), similar to apoprotein B. While, like apoB, it is a bit different in that it includes VLDL, it has proven a superior measure of risk.--LDL particle number--In my view, this is the gold standard for LDL and risk measurement, obtained by only 18% of our poll respondents. LDL particle number is proving superior for discriminating who is truly at risk for a cardiovascular event, particularly when metabolic syndrome or diabetes is part of the picture, i.e., when HDL and triglycerides are considerably distorted, leading to substantial corruption of calculated LDL. While 18% is a minority, it still represents growth in recognition that conventional calculated LDL cholesterol is an unreliable, inaccurate, and outdated value. If the real LDL were to stand up, I believe that it is LDL particle number that would spring to its feet.