# About cholesterol. Are HDL and LDL additive wrt the total figure?
**URL:** https://boards.straightdope.com/t/about-cholesterol-are-hdl-and-ldl-additive-wrt-the-total-figure/236382
**Category:** Factual Questions
**Created:** [March 25, 2004, 6:00pm UTC](https://boards.straightdope.com/t/about-cholesterol-are-hdl-and-ldl-additive-wrt-the-total-figure/236382 "2004-03-25T18:00:53Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)
#### Post date: [March 25, 2004, 6:00pm UTC](https://boards.straightdope.com/t/about-cholesterol-are-hdl-and-ldl-additive-wrt-the-total-figure/236382/1 "2004-03-25T18:00:53Z")
I underwent a cholesterol screening yesterday, and they told me that my HDL (=‘good cholesterol’) was 68. My overall figure was 227 which they said was a little high. But they didn’t tell me my LDL value.
My simple question: Do I get the LDL value by subtracting the HDL value from the total? Or doesn’t it work like that?
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### Author:  [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)
#### Post date: [March 25, 2004, 6:53pm UTC](https://boards.straightdope.com/t/about-cholesterol-are-hdl-and-ldl-additive-wrt-the-total-figure/236382/2 "2004-03-25T18:53:28Z")
No, the total-cholesterol does not equal the LDL-cholesterol plus the HDL-cholesterol.
In fact, total chol = LDL-chol + HDL-chol + VLDL-chol
In practice, direct measurement of VLDL-cholesterol is difficult
So, a close approximation (when triglyceride levels are less than about 400 or so) is used:
Total Chol = LDL-chol + HDL-chol + TG/5
The TG/5 figure is used to approximate this third major source of circulating cholesterol (VLDL-cholesterol) and assumes there’s a fixed molar ratio of TG/cholesterol in all VLDL for everyone. Clearly, not 100% accurate, but not too bad.
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### Author:  [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)
#### Post date: [March 25, 2004, 6:57pm UTC](https://boards.straightdope.com/t/about-cholesterol-are-hdl-and-ldl-additive-wrt-the-total-figure/236382/3 "2004-03-25T18:57:06Z")
Sorry, in the above, I never explicitly defined TG to be trigylcerides.