[Dirk Bakkeren]

You are right that the example unit “%” is not correct. Because UCUM makes use of 7 bit ASCII the promille sign (“‰”) is not available. Not all systems can represent this unit.

However , the correct UCUM notation you suggest is not “/10^3” but “/10*3″. You can check this using the UCUM checker @ https://ucum.nlm.nih.gov/ucum-lhc/demo.html
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[Dirk Bakkeren]

I fully agree Jozef. My notation of mmHG was not conforming to UCUM. Fortunately in our LIS it is :).

[Dirk Bakkeren]

Well this may not always be so easy. Information systems have check the UCUM notation of the units. For blood gas parameters like pO2 and pCO2 (mmHg of kPa) the difference is not a factor 10 but 7.5 (or 0,133 the otherway around). Systems need to check the units received. notation have to be proper UCUM notation otherwise such a check will fail.

[Dirk Bakkeren]

Hi Pam,

I have a question that is closely related to the question of Katherine. We use LOINC code 91671-8  “<span id=”xf-951″ class=”xforms-control xforms-output”><span id=”xf-951≡≡c” class=”xforms-output-output”>Transferrin.carbohydrate deficient.disialo/Transferrin.total standardized per IFCC-RMP for CDT in Serum or Plasma”. However, there are several</span></span> routine methods to perform this test. When people have an increased CDT often a confirmation test is requested, as the consequence of an increased CDT can be the withdrawal of their drivers license.
However, as there is only one LOINC code the confirmation test (HPLC reference method) can not be differentiated from a routine CDT test. How can such an issue be beste resolved?

[Dirk Bakkeren]

Hi Swapna. Do you know how many pre-release LOINC code never made it to the next, or any, publication?

Thanks in advance

Dirk Bakkeren

[Dirk Bakkeren]

Dear Thomas,

I understand your problem with the limited number of ‘systems’ (sample materials) to select from. I had the same hesitation when starting to know LOINC. However, every coding system has to deal with the problem of granularity. With granularity I mean the number of different codes that are used to distinguish results from the same component from slightly different materials. Lab people like you and me are use to appreciate these differences, but for docters the results, even ± 10%, often mean the same. We use different codes to tell our information systems whether results may be presented/compared together (on the same row in an cumulative report) or not.
In The Netherlands we are working on an Dutch susbset of LOINC (and additional SNOMED CT) codes (as not all codes are relevant to us). The LOINC short and long names in the Dutch subset will be translated in the near future.
In an IHE-NL Lab working group we defined a complete HL7 3.0 CDA message structure (from test request to result communication) for which the LOINC code together with the actual units (like mmol/l) and reference range are the pay load. In this message there are additional (optional) fields reserved to give more detailed information about the exact sample material and the laboratory method used. This information must alway be in accordance with information inherant to the chose LOINC code! This extra information is more important for inter-lab communication then for result communication to docters.

There is another problem that is not yet covered, that is the problem of method calibration. It is possible that two labs perform the same assay, use the same LOINC code, but have their methods calibrated differently. We have a couple of examples in The Netherland. Most labs have their enzymes (IFCC methods) calibrated using a very good commutable enzym calibrator (KAL 2000 SKML, Nijmegen, http://www.skml.nl). However, as we are close to the Belgium border, enzyme assays performed in Belgium clinical chemistry labs may have the same LOINC code and units, but at the same time have different reference values, as these assays are calibrated using a different calibration method (i.e. using the molar extinction coeffient of the reaction product). These differences have be solved when exchanging results. Selection of LOINC codes alone is not always enough! The actual chosen units are important (esp. with endocrine assays) as are the calibration method or actual reference ranges (as these also change with a different calibration).

Dirk Bakkeren

[Dirk Bakkeren]

Dear Alice,

You are absolutely right that the BCG and BCP methods are not electrophoresis but dye binding methods to determine albumin. I think the use of LOINC codes including a method should only be choosen only when the assays lead to clinically different results. In that case the assay must have different reference ranges. If you (unnecessarily) select LOINC codes with a specified method field, the receiver of the results has to incorporate the result in his ICT application as a different test. Although de BCG and BCP assay do have slightly different characteristics with resepect to certain proteins/body fluids, they generally are both used to determine albumin in serum or plasma using the same reference ranges. My advise would be to use the ‘albumin LOINC’ for Ser/Plas with none for the method.

[Dirk Bakkeren]

Dear Phillip,

In The Netherlands I have also started to translate LOINC database items to Dutch. I ran into the same questions that you address. I choose to translate 1H to 1u (uur). In a way we follow UCUM, but also in Dutch we never use “U” for “uur”. That is not a problem, as the language variant is only used in your language area. When you exchange the LOINC code with an US lab, they will read the US meaning in their database.

I asked Daniel Vreeman about translating umol to µmol (all uses of u instead of µ). Daniel advised to keep using “u”instead of “µ”. This item is sent into the message so it depends on the computer codepage of the receiever if the code for “µ” is also a “µ” in their code codepage. If everone uses Unicode then it may be solved (I guess). For the time being we use “u”.

Dirk Bakkeren
Clinical chemist,
NVKC, The Netherlands
http://www.nvkc.nl

[Dirk Bakkeren]

Dear Kathy,
The units you mention in your answer are not the correct units for the HbA1c (IFCC) method.
The HbA1c (IFCC) is expressed in mmol (HbA1c)/mol (Hb) NOT in umol/mol. This has international agreement which really can’t be changed.
Can you please confirm that the units in mmol/mol?

Best regards
Dr Dirk Bakkeren

[Dirk Bakkeren]

Dear Pam,

I am talking about the low to high reference range of normalcy. We are using HL7 2.2 and 2.4 depending on the protocol. For some communication other protocols are use like Edifact.

Dirk Bakkeren, pHD
Clinical chemist
Máxima Medisch Centrum
Veldhoven – The Netherlands
Dutch Society for Clinical Chemistry and Laboatory Medicine (NVKC)

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