Why Are There Different Ways Of Calculating Your Total Cholesterol?
April 24th, 2009 | 
Author: My sister says your total cholesterol should be your HDL + LDL. However, on my last blood test, my HDL + LDL was 10 points lower than my total cholesterol. So, I found some web sites that have the following formula:
HDL + LDL + (Triglyceride * 20%) = Total Cholesterol
The formula above does work to give me my total cholesterol given the other #’s (HDL, LDL, and Triglycerides) on my last blood test results. But, I want to know why my sister’s always come back as:
HDL + LDL = Total Cholesterol
Some web sites say to calculate it one way and others say the other way. Anyone know why they would be different?
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Technically, there is no pure cholesterol in your bloodstream. Cholesterol is transported by lipoproteins. LDL (low-density lipoproteins) and HDL (high-density lipoprotiens) are the lipoprotiens used to transport cholesterol.
Tests can be run that actually test for the cholesterol, which gives you the total cholesterol number (direct measurement). Or you can run a test for the HDL and LDL cholesterol complexes. You add these values to get a computed total cholesterol.
If you run a total cholesterol AND compute it from summing the HDL and LDL cholesterols they should be close, but won’t agree exactly. Tests have a margin of error. This is why they won’t match exactly.
Though triglyerides are often transported by lipoproteins, I don’t know why they would use it to compute total cholesterol.
We used to run total cholesterol then and HDL, computing the LDL as a difference between the total and HDL.
A correction to the answer above this – folic acid is not a fatty acid.
well, I think that one day some scientist discovered that if you get bored enough you can find different ways to do things. Like the Total Cholesterol. What it is, is that you take the common ingredience in all food, then add it together. Everything has the same base that you have to go off of in order to make what you want. Take for instance, chicken and hamburger. They both have some form of “fatty” acids (Folic acid). That is like the base. Then you find the next common ingredience and you have your cholesterol.