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How are Triglycerides Measured?

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  • How are Triglycerides Measured?

    Let's say your triglycerides are 57. What was actually measured to get this number? Since the triglycerides are not floating in the bloodstream, they must look for it inside of "cholesterol". So my question is what types of cholesterol are examined to get a triglycerides amount?

    Triglycerides are in chylomicrons (and remnants), VLDL and IDL (and remnants), LDL, and HDL. I'm thinking the number we see on a lab report is not really the total triglycerides in the blood, but some subset of total.

  • #2
    To my understanding a person has triglycerides in virtually all chylomicrons, HDL particles and LDL family particles (VLDL, IDL and LDL) along with any remnants. The triglyceride molecules are packaged inside the lipoproteins along with cholesterol/cholesteryl ester molecules. The cholesterol is not examined for triglycerides. The number that the standard cholesterol panel reports for triglycerides should be the total triglycerides per mg/dL.

    Here is a pictorial of several lipoproteins, and the triglycerides are typically colored blue with cholesterol/cholesteryl ester colored yellow.

    Here is an excerpt from a triglyceride lab assay test in case you are curious:
    PRINCIPLES OF PROCEDURETriglycerides are enzymatically hydrolyzed by lipase to free fatty acids and glycerol. The glycerol is phosphorylated by adenosine triphosphate (ATP) with glycerol kinase (GK) to produce glycerol-3-phosphate and adenosine diphosphate (ADP). Glycerol-3-phosphate is oxidized to dihydroxyacetone phosphate (DAP) by glycerol phosphate oxidase (GPO) producing hydrogen peroxide (H2O2). In a color reaction catalyzed by peroxidase, the H2O2 reacts with 4-aminoantipyrine (4-AAP) and 4-chlorophenol (4-CP) to produce a red colored dye. The absorbance of this dye is proportional to the concentration of triglyceride present in the sample. This analytical methodology is based on the reaction sequence described by Fossati et al.4 and by McGowan et al.5In this reagent, 4-chlorophenol is used rather than 2 -hydroxy-3,5-dichlor-obenzenesulfonate, used in the Fossati and McGowan studies
    Last edited by Tom; 07-27-2019, 09:58 AM.


    • #3
      Thanks Tom. That is exactly what I was looking for. Wouldn't it be helpful to know how much of the triglycerides was being carried in each type of lipoprotein?

      What got me thinking about this was cholesterol remnants. The formula tot chol - (LDL + HDL) = Chol Remnants is used. If remnants is under 17, that is supposed to be optimal; but it seems to me that without knowing what is causing a person to have remnants, the number is only relational at best. A person might have cholesterol in VLDL/IDL or their remnants or even chylomicron remnants.

      OK, how did I get from triglycerides to VLDL?
      VLDL is equal to triglycerides divided by five, so substitute accordingly in the equation:

      Triglycerides/5 = total cholesterol - HDL - LDL

      Another article explained where the 5 comes from:

      The ratio of the mass of TG to that of cholesterol in VLDL is about 5:1.

      Since the amount of triglycerides in VLDL decreases as cells take it in, the 5:1 ratio only applies to new VLDL.

      I was looking at my recent cholesterol lab trying to see if I could get any insight into chylomicron, vldl, or idl remnants, and I guess the answer is no. I see a lot of articles saying that a test is needed for remnants, but I guess there is not a standard lab I can order that would give me this information.
      Last edited by rich; 07-28-2019, 06:55 AM.


      • #4
        This is a topic that I am interested in, but it seems to be difficult to make a lot of headway using standardized testing. One interesting thing that I have come to recognize is that most LDL-C results are calculated and not directly measured using the formula you listed above. Although the articles that I have seen indicate that calculated LDL-C values are generally close enough to direct measurements, I am seeing a significant difference between the two values when I consider my recent direct measurement LDL-C values vs. what the calculated values would be. I am overseas, and so perhaps this is just an issue with the lab I am using.

        If there is a significant difference between those two values, then I have to wonder if the triglycerides/5 rule really holds true for remnant cholesterol. As a start the triglycerides/5 rule is only roughly valid when the triglycerides are not high, arbitrarily under 150 mg/dL (somebody may know of a lower limit). If you use that remnants under 17 thought as valid, then using a calculated LDL-C value brings in another potential error. If I use a calculated LDL-C value, then essentially the remnant score becomes the triglycerides/5 and 17x5=85 mg/dL for max triglycerides. Well, although that kind of sounds good, I am not so sure it is definitive. Perhaps I made some mistake in the math.

        In the end I think that LDL-P is really a better marker than LDL-C, and after getting one advanced lipid profile I can get a general idea of whether I am doing well based upon my triglycerides level. If my triglycerides are kept under 80 mg/dL, I should make less VLDL particles that become sdLDL particles. I will make less ApoCIII protein which clogs up clearance of LDL and HDL particles resulting in sdLDL and HDL particle that are very large but not effective in clearing cholesterol/cholesteryl ester.
        Last edited by Tom; 07-28-2019, 02:57 AM.


        • rich
          rich commented
          Editing a comment
          Tom, that's the circle I found myself in yesterday as I was researching this. These formulas at best are accurate if everything is working as it is supposed to. They make the assumption that if you are fasting, there are no chylomicrons or their remnants in the blood. It seems to me it would be critical to know how many chylomicrons, vldl, idl are in the blood when they do the lipids analysis.

          Something I find interesting is that as I make my discoveries, then I have new search terms to use and find that others made these discoveries years ago. The literature is out there, but unless you know what to look for it is often not easy to find. This would be a great app for someone to make.

          My triglycerides are under 80, yet my LDL particle number is mid range. I had my doc retest for leaky gut as that was the only idea I had as to cause. I have been eating a half/half baking mixture of spelt and flax seeds for making muffins. It might be that the gluten in the spelt is the problem, so I changed from spelt to oat flour.

          I also asked her to retest bacteria and she suggested a heavy metals panel as well. Waiting on the results from those labs. My most recent lipids panel was not quite as good as the one I had 4 months ago, so we are looking for possible causes.
          Last edited by rich; 07-28-2019, 07:23 AM.