Medical Conversions (Lab results)

[JohnS]

The U.S. medical profession uses different reporting units than the rest of the world for lab results. U.S. results are usually reported as mass/volume, such as milligrams per deciliter (mg/dL) while the rest of the world uses amount of substance/volume, such as millimoles per liter.

Conversion requires knowing the molar mass (molecular weight) and correcting for different reference volumes.

JAMA (Journal of the American Medical Association) publishes this conversion guide for authors:
http://jama.ama-assn.org/misc/auinst_si.dtl
EDIT: Dead link as they update their Manual of Style. Scroll down through later posts to find the current link.


They focus on "practical" accuracy, frequently 3 significant figures. Higher precision could be obtained by researching the correct molecular weight, but these suffice for JAMA publication and real world reproducibility of lab tests.
(Note: The tables have a frequent typo of "moI" instead of "mol".)

The table does not include blood pressure. The U.S. uses millimeters of mercury (mm Hg) whereas the rest of the world uses kilopascals (kPa). Exact: 760 mm Hg = 101.325 kPa. Convenient, practical accuracy: 750 mm Hg = 100 kPa, so divide by 7.5 mm Hg/kPa.

[Mrs X]

Here is another useful converter: You can loook up the substance, and convert to the units you want.

http://home.vicnet.net.au/~ncrick/converters/molecular_mass.html

From ncricko, as a response in the conversion forums.

[ross]

John,
Just curious, are you a medical researcher, MD, mathematician or perhaps all of the above?

You can certainly answer my question, if you would be so kind:

I have lab results that are given in mg./L and I want to convert them to mg./deciLiter. Do I multiply the mg./L by 0.1?

(I should know how to do this, but am now old, sick and sick of being sick.)

I do look forward to hearing from you. Ross

[JohnS]

John,
Just curious, are you a medical researcher, MD, mathematician or perhaps all of the above?

You can certainly answer my question, if you would be so kind:

I have lab results that are given in mg./L and I want to convert them to mg./deciLiter. Do I multiply the mg./L by 0.1?

(I should know how to do this, but am now old, sick and sick of being sick.)

I do look forward to hearing from you. Ross

No, I am an engineer by training; I have NO medical background whatsoever. I worked in automotive, which is metric and I am much more comfortable using metric units than US Customary. Most of the questions we get involve understanding of the metric system or units in general.

On the medical questions, I can only help convert the results if necessary, not help with what the results mean. I answered your specific question in your other thread, but you have it correct.

[JohnS]

The link in post #1 now generates a "page not found" error. Poking around the JAMA site, it appears to be replaced by this new page:
http://www.amamanualofstyle.com/oso/public/jama/si_conversion_table_2.html
EDIT: Dead link, scroll down for current link

Most of their "Manual of Style" is only available to subscribers, but this page is open to anyone.

[Mihaela]

Does anyone know how to convert ug/100mL ( ug = microgram..) to
mg/L ?
One of my new equipement in lab insist to show me the results in mg/L .
I modify in parameters and my curve is a line .

[JohnS]

Does anyone know how to convert ug/100mL ( ug = microgram..) to
mg/L ?
One of my new equipement in lab insist to show me the results in mg/L .
I modify in parameters and my curve is a line .

Divide by 100 to get µg/mL

Since 1000 µg = 1 mg and 1000 mL = 1 L, µg/mL = mg/L

[JohnS]

The AMA has again updated their Manual of Style. The whole book is by subscription only, but the SI calculator remains open to anyone. New link is:
http://www.amamanualofstyle.com/page/si-conversion-calculator