Two LOINC codes for one lab-item

Bert Verhees bert.verhees at
Wed Feb 15 06:42:55 EST 2017

Thanks Ian for the quick response.
>From practical point of view you are right.
I think we need follow this advice.

But now let's look at it from the Reference Model or LOINC point of view,
maybe there some change would be welcome.

The problem is that different used units in measurements which are exact
the same for the rest (method, substance, purpose), sometimes translate to
a different LOINC-code.

In openEHR-archetypes (mostly used to build software) we want to constrain
the sender in the units he can choose. We don' t want our software to
translate every possible unit to the unit we want to process. So that is
why we offer some units for the sender to choose from. This constraining is
done in DV-QUANTITY, following the openEHR-specs it is in UCUM syntax (it
does not say UCUM-unit

To be sure that the sender is using the constrained units and measuring the
constrained item we need some coding. I was worried because of some
discussion on an OpenEHR list in 2014, which discussed a similar problem. (

So, imho, the possibility to add LOINC-coding (or coding in general) to
different unit-kinds in the dv_quantity-class to tell us what we are
looking at, would be a good feature to support interoperability.

Bert Verhees

Op wo 15 feb. 2017 om 11:53 schreef Ian McNicoll <ian at>:

> Hi Bert,
> I don't think this is helpful. The source of truth in dv_quantity should
> always be the unit. I would not trust the LOINC code. It should be the
> responsibility of the original sender/documenter to make sure the correct
> LOINC code was used to match the SI unit. I would think this advice would
> apply whether one was using hl7v2, FHIR, CDA or openEHR.
> Ian
> Dr Ian McNicoll
> mobile +44 (0)775 209 7859 <+44%207752%20097859>
> office +44 (0)1536 414994 <+44%201536%20414994>
> skype: ianmcnicoll
> email: ian at
> twitter: @ianmcnicoll
> Co-Chair, openEHR Foundation ian.mcnicoll at
> Director, freshEHR Clinical Informatics Ltd.
> Director, HANDIHealth CIC
> Hon. Senior Research Associate, CHIME, UCL
> On 15 February 2017 at 10:37, Bert Verhees <bert.verhees at> wrote:
> Hi all,
> When you work with quantities it is possbile to add more units, sometimes,
> the use of different units have other LOINC-coding, this is for example with
> LOINC LongName
> Component    Scale      exUCUMunits
> 2160-0 Creatinine [Mass/volume] in Serum or Plasma        Creatinine
> Qn         mg/dL
> 14682-9 Creatinine [Moles/volume] in Serum or Plasma      Creatinine
> Qn         umol/L
> Would it be good if it was possible to add code per unit-kind in
> dv_quantity?
> Or are there other suggestions
> Thanks
> Bert Verhees
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