Confused over Blood test readings


(Ronald Weaver) #1

Somewhat confused over my readings on my last blood test…
My Triglycerides are 0.62 g/l and underneath is a measurement of 0.70 mmol/l
Cholesterol HDL is 0.67 g/l and also a measurement of 1.73 mmol/l

Does that look right to you ?


(Bacon is a many-splendoured thing) #2

I’ve never seen measurements in grams /litre before, but if that’s what the lab reports. . . . The measurements in millimoles/litre are more usual (though not in the U.S.).

By the way the ratio of triglycerides to HDL, 0.7 / 1.73 = 0.4, which is excellent. You want the ratio to be less than 0.9.


(Ronald Weaver) #3

Thanks for the reply Paul.
Yes, Trigs/HDL in mmol/l looks fine at 0.4, but if you do the calculation in g/L it gives you 0.92. Not so good ? So I’m still confused.
They started introducing millimolar measurements in the early sixties, I think that’s why I gave up chemistry and and aimed at becoming a bullfighter…


#4

Nope, are you positive on those units? It’s usually mg/dL or mmol/L, what country are you in?


(Joey) #5

Converting grams per liter (g/l) into milligrams per deciliter (mg/dL) ought to go something like this:

1,000 mg in a gram… (so times 1000 in the numerator)
10 deciliters in a liter… (so divide by 10 in the denominator)
and 1000 divided by 10 = 100.

So net conversion: multiply your g/l figures by 100 to obtain mg/dL
(i.e., move the decimal place over two spots to the right)…

But it’s still unclear as to whether you have all the correct figures cited in your post, given that the ratios are markedly different depending on the units.

Please check your post for accuracy and see if anything needs to be adjusted?


(Bacon is a many-splendoured thing) #6

Ah, but the magic number is different for measurements in mg/dL. So . . .

Your triglycerides = 0.62 g/L => 62 mg/dL

Your HDL = 0.67 g/L => 67 mg/dL

The ratio is therefore 62/67 = 0.93.

When the ratio is derived from readings expressed as mg/dL, you want it to be under 2.0, so whether you look at 0.4 or 0.93, either way, at less than half of the target number, you are fine.


(Ronald Weaver) #7

France.


(Ronald Weaver) #8

Thanks, Paul. I’ve checked and double checked the figures on the report from the Laboratoire and that is what’s printed.
But your explanation makes everything clear, thanks again !


(Joey) #9

@Ronald_Weaver Yes, either way your levels are looking good. But this still leaves me confused about something …

Regardless of the units a lab uses for reporting Trigs and HDL, shouldn’t the ratio between the amount of each be the same proportion, regardless of standard of units applied to get to the ratio?

Both mg/dL and mmol/L are expressions of “mass divided by volume.”

Regardless of which measuring framework is used, in terms of basic physics, how could you get a ratio of both 0.4x and 0.9x from the same test?

Unless I’m missing something here, this doesn’t seem possible mathematically. :man_shrugging:


(Bacon is a many-splendoured thing) #10

No, because a mole of one chemical will generally have a different weight from a mole of another chemical. The molar weights depend on the chemical formulas of the substances involved. So a mole of triglycerides will have a different weight from the weight of a mole of HDL. To get the mass equivalents of these amounts will therefore require multiplying by different factors. (If the two chemicals have the same chemical formula, of course, then and only then will the multiplying factors be the same.)

So triglycerides and HDL measured in terms of weight per unit of liquid will give one ratio, and triglycerides and HDL measured in terms of the number of molecules (molar amount) per unit of liquid will give a different ratio.


(Bob M) #11

Weird.

But…

The only thing I can think of is the two items have different densities. For instance, trigs are larger, fluffier, HDL not.

Like this:

http://healthy-ojas.com/cholesterol/lipoprotein.html


(Bacon is a many-splendoured thing) #12

The weirdness results from the fact that moles, decimoles, centimoles, and millimoles are all numbers of molecules, whereas kilograms, centigrams, decagrams, grams, decigrams, and milligrams are all measures of mass. And since most substances that we are comparing have different chemical formulae, a mole of chemical X is generally going to have a different mass from a mole of chemical Y, unless X and Y have the same chemical formula, arranged differently.

There are 6.02 × 1023 molecules in a mole, and a given substance’s atomic weight is the mass of a mole of that substance, expressed in grams.


(Bob M) #13

I get it. No need to explain. I took college chemistry, so I remember some of it.

Paul, you might consider trying to not always be “right” or more knowledgeable than anyone else.


(Joey) #14

Ha! :laughing: Same, same … chemistry is a distant memory now. The more mass increases while volume decreases, the more I become dense.

But I’m glad Paul is always right. Saves me the trouble of trying too hard.


(Ian) #15

Glad to see another chemist in da house! Mass, moles and good old Avogadro’s number were always a tricky beast to get a grip with.