RAST interpretations

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  • #16179
    Doug Mitchell

    I’m trying to LOINC a test from an outside lab. The outside lab has given us a LOINC code, but I’m not sure it’s correct. The LOINC code they have assigned is:

    33536-4 Allergen.miscellaneous Ab.IgE.RAST class ACnc Pt Ser Ord

    The “value” of this test code is a text string as follows (I’ve tried to remove any identifying information about the performing laboratory):

    REFERENCE INTERVAL: Allergen, Interpretation
    Less than 0.10 kU/L: No significant level detected
    0.10-0.34 kU/L: Clinical relevance undetermined
    0.35-0.70 kU/L: Low
    0.71-3.50 kU/L: Moderate
    3.51-17.50 kU/L: High
    17.51 kU/L or Greater: Very High

    Allergen results of 0.10-0.34 kU/L are intended for
    specialist use as the clinical relevance is undetermined.
    Although increasing ranges are reflective of increasing
    concentrations of allergen-specific IgE, this may not
    correlate with the degree of clinical response or skin
    testing when challenged with a specific allergen. The
    correlation of allergy laboratory results with clinical
    history and in vivo reactivity to specific allergens is
    essential. A negative test may not rule out clinical
    allergy or even anaphylaxis.
    Performed by an outside lab,
    Street Address, City, State Zip
    URL, Lab Director Name
    Performed at Reference Laboratories, City, State

    What happens is a patient gets multiple individual allergy tests done. Each test is resulted with a number, and the units, “kU/L”. Then 33536-4 is sent with the value as shown above. I’m not quite sure if this is even LOINC-able, as it really is a reference range, or a “do it yourself” RAST class. The clinician would take the numeric value of each allergy test, then look at this text glob to decipher the RAST class.

    Is this the right LOINC for this test?

    Pam Banning


    There’s several variables here: the segment is passed as a Note in HL7. This isn’t coming across in OBX-3, where LOINC is intended to reside. Is that correct?

    They’re giving a numeric answer for each allergen in another portion of the record, and this is one generic interpretation that helps guide clinicians to one of six possibilities: No significant level detected, Clinical relevance undetermined, Low, Medium, High, and Very High. These would be more nominal in scale, if they were being transmitted independently for each allergen. As opposed to ordinal.

    Would like to think of the whole canned text as more of a narrative scale; however LOINC hasn’t create interpretation/impression codes for a single analyte in the past. And this particular field doesn’t contain any patient specific result.

    In checking usage in our Healthcare Data Dictionary, clients have non patient concepts such as Allergen Class/Score, Allergen Interpretation, Allergen Reference Ranges, as well as patient specific interpretations on individual allergens. Wanted to affirm that other labs are trying to relay the same type of information. Following Regenstrief’s policy, we haven’t submitted them for new LOINC codes.

    In my opinion, the lab is using the closest LOINC they can get.

    Hope this helps,

    PC Ho

    We have a list of allergan test (skin prick test) for which are record in diameter (mm) in result entry and LIS test setup as free text. There’re same components in RELMA with different property and unit, should we submitted or treat as local code?

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