With a few very rare exceptions we have not distinguished two tests based on power of the differences in their units of measure. The main down side of this proposal will be the precedent of systematically making such a distinction.
Your request is focused on dimensionless quantities such as you exemplify below- and those will likely be the only ones for which you need that approach because very few other tests in
Canada will have more than one unit of measures. In the US there will be demands for others .
So we have to have a clear justification for this that will prevent us from rolling down the hill to include all units as distinctions.
There is a deeper problem for some terms however. The cell counts NFr's are defined specially in the component.
Which say X Cells/100 Leukocytes. so if there were 6 per 100 WBCs the value would be 6 and the units would appropriately be %
If we were to define pure fractions, I think they would have different component e.g
X cells/Leukocytes - it will not read as obviously- but think that would get you the pure fraction. and we could leave the property alone
How do people name these cell fractions on clinical reports.
In the case of hematocrit the name is defined a percentage in the first three definitions I looked up on the web. Not sure if that would hold up with further digging -- but worry that the imposition of the SI goals in these cases may have created collisions with long term usage and definitions. And we might need another name here as well. How are hematocrits named when reported as pure fractions?
Could I see the whole list of 400+ terms to see what other cases come up? Think we could accommodate the blood counts with new component names-- if they would be tolerable
Think we could make a case for the blood cell counts, worry more about the other ratios that end up dimensionless.

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Intervention
MeSH
Blood components
D006400
The hematocrit ( Ht or HCT ) or packed cell volume ( PCV ) or erythrocyte volume fraction
(EVF) is the percentage (%) of the concentration of red blood cells in blood . It is normally about 45% for men and 40% for women.
[1] It is considered an integral part of a person's complete blood count results, along with hemoglobin concentration, white blood cell count, and platelet count.
On 11/30/2011 5:40 PM, Gilbert Hill wrote:
2011-11-30
Clem,
I write to propose an item for the LOINC committee meeting of December 9, 2011.
You will recall our activity in 2004-2005 related to dimensionless quantities. At that time you and I discussed the need to distinguish results reported with the unit % versus results reported with the unit 1 (and therefore without a visible unit). Following the failure of that exercise, we
(eCHN) continued with our practice of using the ‘authentic’ LOINC code for dimensionless quantities reported as a percent, and creating new Z codes for such quantities when expressed as a decimal fraction. Currently we have approximately 400 Z codes, of which I show three

examples to illustrate the ‘twinning’ involved (all of the principal attributes of each pair are the same).
LOINC Component Property System Scale Example Result
13047-6 Plasma cells/100 leukocytes NFr Bld Qn 6 %
Z1392 Plasma cells/100 leukocytes NFr
13992-3 Albumin/protein.total
Z1045 Albumin/protein.total
MFr
MFr
Bld
Urine
Urine
Qn
Qn
Qn
0.06
54 %
0.54
4544-3 Hematocrit
Z350 Hematocrit
VFr
VFr
Bld
Bld
Qn
Qn
42 %
0.42
Leukocyte differentials account for the largest number of our Z codes, although expression as an NFr is always secondary to expression as an NCnc.
While we are committed in principle to the System International of Units (SI), and while the SI has a stated preference for the use of the decimal fraction notation rather than the percent notation, the unfortunate fact-of-life is that both notations are in use in Canada. If we are to produce interoperable health records it is essential that we distinguish between the two, and the obvious way is to have different LOINC codes.
I have reviewed the relevant events of 2004 and 2005 as found in our correspondence and notes, and these can be summarized as follows (the full documents are attached to this e-mail):
040113a_to Clem: I outlined the problem of dimensionless quantities and the difficulties arising from the fact that LOINC provided no way to distinguish between results reported with the unit % (percent) and results reported with the unit 1 (and therefore no visible unit).
050606_post LOINC committee meeting notes: Note 4. Dimensionless quantities: committee accepted very reluctantly need to distinguish % and decimal fraction; JGH to submit formal proposal for next meeting (probably Dec 2005), including list of items for this processing
051127_to Clem: I suggested the two could be distinguished by creating a subpart of the
SCALE field – e.g. QN^PC if percent, and QN^DF if decimal fraction
051202a_fr Clem: You agreed with need for distinction . . . but concluded with “. . . still think property slot would be the best place to put your proposal . . . “
051202b_to Clem: I agreed with your suggestion to put the identifier in the property field, for example as NFr^PC or NFrDF
051202c_fr Clem: You suggested use of hat (^) after property, and % rather than PC – and prepared a proposal for the committee meeting.
Sad to say, at the meeting of 2005-12-05/06, the committee was not convinced of the need for action and the proposal was rejected.

In re-opening the topic at this time, I wish to propose a solution slightly different than agreed in our correspondence of 2005-12-02. That proposal was that the distinguishing feature would be the use in the property field of something like NFr^PC or NFr^DF, where PC implied percent, and DF implied decimal fraction. By extension, there would then be MFr^PC and MFr^DF, etc.
That would still be acceptable, but the recent appearance in the property field of MoM, replacing the conventional property of RelRto suggests an alternative. From my perspective,
MoM is simply a sub property of the super property RelRto, a different way of expressing the numeric value of the result obtained from an individual patient. The MoM model sets an important precedent, which could be cited as support for the following: for results with the super property of NFr, one could invent, for example, the sub property NFrD (or DNFr), implying number fraction-decimal, MFrD (or DMFr), implying mass fraction-decimal, etc. I do not think there would be a need to change the current NFr to NFrP, implying number fraction-percent.
Obviously, other text strings, with or without the hat (^) could be used instead of the examples
I have given and suggestions would be welcome.
We (eCHN) are presently involved in a complex project to merge certain functions of the eCHN with the provincial laboratory information system, known as OLIS (Ontario Lab Information
System). In the course of this project the predicted difficulties arising as the result of failure to distinguish between the percent and decimal fraction notations have become a major problem, involving much frustration and the investiture of significant amounts of time and intellectual capacity. There is an urgent need to resolve this problem, which no doubt will continue to surface as the pan-Canadian electronic health record project moves ahead, and I hope the committee will respond by supporting, at least in principle, some action now. Assuming agreement in principle, we should be able to work out the specific details fairly quickly.
I look forward to your comments.
Gil