Same units in different Property?

Im looking for some info regarding units and Property. I always thought that a unit was exclusively assigned to just one Property, but filtering the Loinc excel table i easily realize that’s not the case. Can anyone explain me whats the rational behind assignement between unit and Property?

Thank you

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Hello David and welcome to the community!
The properties for numeric measurements can be tricky to begin with. Mass concentration is any portion of a gram weight / any portion of volume measurement in liters. MCNC is the property for assays reported in g/L, mg/mL, ng/dL, etc…any portion of a gram/any portion of a liter.

Substance concentration is any portion of a molecular weight / any portion of volume measurement in liters. SCNC is the property for assays reporting in mole/L, millimole/milliter, nanomole/deciliter.

I won’t complicate this response further with timed units of measure, but please be sure to respond and continue the discussion.


I agree there is no single cardinality, one-to-one mapping between units and property.
The “kind of property” is further defined by scale and sometimes by timing.
It makes it more difficult to automate and requires more analysis on the part of LOINC mappers.
Fortunately, there is a lot of documentation to help with individual cases.
Diane Carter, CLS, MPH, and L’oincing since 2000.

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Hello Pam
Thanks for answering my question. My point was pretty much what Diane Carter said. I understand that that multiple units are related to the same Property but some of them are not exclusive as they can be found in other Property’s. Percentagem “%” is one paradigmatic example i guess.
Isn’t the Unit enough to define one specific Property? What elements should take in consideration to establish this relation properly.

Thanks in advance
Best regards

Hello Diane
Thanks for helpping. I see you probably face this difficulties a lot more than me. Where can i find this documentation? Any suggestion?

Best regards

Hi David,

Percentages are a quantitative situation where one needs to look at the component and divisors to identify the correct “fraction”.
Cells xyz/100 cells = % = Numeric fraction
In Canada, where the answers are expressed in decimal format and not percentages, NFR.DF

In chemical analysis, one would need to consider the metric or molar weight of the component and divisors prior to division. Hemoglobin A1c/Hemoglobin have both MFR and SFR available for percentages.

I believe between the component and property attributes with the unit of measure, you should have the right data elements to relate.

Let me know of further questions,

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