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Tips to Identify the Correct LOINC Scale

 LOINC is based on a six-axis perspective of what is being evaluated: component, property, timing, system, scale and method. Scale is a reflection of the data type or format of the result.

  1. Text answers can have the scale of Ordinal (ORD), Nominal (NOM) or Narrative (NAR):Apr2017LabLOINCScales

    1. ORD: Opposites or ranking answers (Positive/Negative, Detected/Not Detected, 1+, 2+)

    2. NOM: Non-sequential, non-related answers (Yellow, Green, Cloudy)

    3. NAR: Free text results that are not predefined as the previous two

In addition to selecting the correct scale, there are LOINC terms with prescribed answer lists. These are listed on the View Details tab in RELMA.  The normative lists MUST be adhered to; they usually belong to copyrighted surveys.  If your answers don’t match a normative list, do not use that LOINC term.  An example is the OASIS survey; one of its many components is 57216-4 Ability to Hear with four specific answer choices.   

  1. There’s a relationship between the property and scale attributes. 

    1. The property of Arbitrary Concentration (ACNC) when it occurred together with the scale of ORD have been replaced by the PresenceThreshold (PRTHR) property (scale remains ORD) starting in 2016.  Therefore, don’t look for ACNC/ORD in RELMA.  ACNC is still the property for quantitative values (scale is QN) using International Units/volume (e.g., IU/L) or an arbitrary Units/volume (e.g., U/L).

    2. The properties of Mass Concentration (MCNC), Substance Concentration (SCNC), Mass Concentration Ratio (MCRTO) and Substance Concentration Ratio (SCRTO) all have the scale of QN.

    3. Susceptibility is the only property to use the Ordinal/Quantitative (ORDQN) scale. This allows for either interpretation of Sensitive, Intermediate or Resistant, OR antimicrobial concentration reporting (MIC or KB values).

    4. The property is Titer (TITR) and the scale is QN when the titer is included in the answer, for example, Neg@1:16 or Pos@1:20. Don’t choose PRTHR/ORD instead of TITR/QN by mistake.

Choosing the right scale is critical when LOINC is being used to aggregate data. It keeps similar data types together.  If you have questions or would like assistance with LOINC implementation, please contact us.

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