New And Improved LDL Lab Numbers

–Lab companies start reporting more accurate LDL cholesterol measurements.

The LDL cholesterol number, which has been the obsessive focus of physicians and patients for several decades now, is getting a major upgrade. A new and improved method to calculate the LDL cholesterol number is starting to filter into standard laboratory reports.

Until now LDL cholesterol, which is not measured directly by standard blood tests, has been calculated using the Friedewald equation using standard lipid profile data. But the Friedewald equation is a blunt instrument, and it becomes increasingly unreliable at the low LDL levels achieved in patients taking intensive lipid lowering therapy. The new more accurate calculation is based on research performed by Seth Martin and colleagues at Johns Hopkins.

Quest Diagnostics is the first national laboratory to incorporate the new equation in its lab reports. Martin said that he hoped that Labcorp, the other lab giant, and smaller labs would also convert to his new method. (Martin said that Johns Hopkins has a pending patent on the algorithm.)

“Our algorithm and the Friedewald equation both use the same standard lipid profile data and both divide triglycerides by a number to estimate VLDL cholesterol, but the difference is a personalization vs one-size-fits-all strategy,” Martin explained. “Our algorithm selects the division factor out of 180 choices based on the one that best fits the patient’s lipid profile, whereas the Friedewald equation divides everyone by 5. Dr. Friedewald et al said in their original paper, ‘Simple division of the plasma TG by five does not give a very accurate estimate of VLDL-C’. They tolerated the inaccuracy since patients weren’t being treated down to low LDL-C so the estimate was a relatively less important part of the equation. At that time, statins, Zetia, and PCSK9 inhibitors did not exist. Whereas they had a 400 person dataset, we had over a million, which allowed us to take the personalized approach.”

James Stein (University of Wisconsin), said that the “revised conversion factor better reflects the cholesterol component of VLDL. It is empirically derived and is an advance. It will be especially useful in people with very low LDL-C and as triglycerides increase.”

The improved LDL number produces a risk estimate that is more concordant with non-HDL cholesterol, which many lipid experts say is the preferred number to use in risk calculations. “When our algorithm says that the LDL-C is actually above the guideline cutpoint, non-HDL-C tends to be too,” said Martin.

Martin emphasized that the change in LDL calculation does not alter the way people should interpret the LDL number. It is just a more accurate reflection of the amount of LDL. “This is an equivalent reference value for each equation. One interprets LDL-C the same way. The point here is not about recalibrating guideline cutpoints but about getting precise information on the patient to make the best decisions together with them,” said Martin.


  1. John McCall says

    LDL has been an obsessive focus driven by big pharma and big food in the USA. Same on them. So much time, effort and money wasted in the face of the obesity epidemic.

  2. Instead of guessing, calculating, estimating it is not better to measured the LDL, VLDL, HDL subfraccions and the amount of particles. In my local large Hospital last year 64% of the dead patients with CVD etc died with low total cholesterol and low LDL.

  3. An elderly and now long retired consultant told me ages ago that back in the day when he saw high “cholesterol” the first thing he did was check TSH, but at some time in the seventies/eighties this relationship ceased to be true. I’ve read much the same from some still-practising doctors. Presumably the thyroid/cholesterol connection was broken by the massive increase in insulin resistance following “low fat” diets.

    I personally experienced the same thing – when my thyroid went high my LDL dropped by almost exactly the same amount as the statin used to produce – yet curiously it was when my thyroid was highest and my LDL lowest that my leg arteries furred up, and since the thyroid came under control the arteries improved significantly. Things that make you go “hmmmmm” . . .

    Apart from that obvious confounder, through over 12 years of LCHF/Paleo/keto diet my body “likes” my HDL to be over 50, my trigs under 100 and my LDL around 150. Who am I to disagree? The numbers are so consistent I no longer bother with lipid panels. As long as my blood glucose (and presumably insulin) stays resolutely normal and my BP does so on a low and consistent dose of Amlodipine I’m not too worried. It took considerable arm-twisting to get CRP (2 while my arteries were still inflamed) and D3 (95 – both UK numbers), while an NMR, homocysteine, fasting insulin or preferably a full Insulin Assay are completely unavailable – all things which might be highly useful.

  4. Richard Glasser says

    I have been very pleased with this new calculation method and as a result, I can stop ordering Direct LDLs on patients going to Quest Labs. I would encourage LabCorp to switch as soon as they can.

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