Please change kIU/l to KUA/l

[timbrisc]

Issue migrated from trac ticket # 5800

component: help | priority: blocker

2022-02-11 17:36:20: joanne.m.yancon@thermofisher.com created the issue

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Thermo Fisher Scientific is requesting kUA /l to be represented as the standard unit for allergen specific IgE results.

When reporting results for an allergen-specific IgE antibody test, the notation should clearly indicate the result is a measurement of a subset of IgE antibodies and not total IgE immunoglobulin. By including a subscript “A” it is clear the result is for allergen-specific antibody. Measurements of both allergen-specific antibodies and total IgE immunoglobulin are concentrations and requires expressions of volume.

Specific IgE antibodies are expressed in (kUA/l) where A represents allergen-specific antibodies, and Total IgE values are expressed in kU/l

[timbrisc]

2020-11-11 15:14:58: mitchbre@regenstrief.org changed status from new to closed

[timbrisc]

2020-11-11 15:14:58: mitchbre@regenstrief.org set resolution to spam

[dr-shorthair]

Original issue title:

Previously submitted ticket #5790 was closed. Not sure if my request to change the current LOINC reporting was understood. Please change kIU/l to KUA/l - see below for explanation. I am also able to send the ImmunoCAP Specific IgE Directions for Use as a reference but I am not sure how to attach a document. This may be found on line also. I apologize for not responding sooner but we are now just receiving questions on this again.

[dr-shorthair]

k[AU]/l is an existing valid UCUM code, where [AU] = "allergen unit | procedure defined amount of an allergen using some reference standard"

There is also a note:

The unit “AU” (for allergen unit) is for the amount of an allergen based some procedure defined and allergen specific reference standard. Note, do not confuse with astronomical unit, distinguish [AU] from AU

Note also that [U] is a different unit:

The unit “U” of enzymatic activity was defined in 1964 by the International Union of Biochemistry as the catalytic activity that catalyzes the transformation of 1 μmol of the substrate per minute. This unit is defined so that normal biological enzyme activities are in the range of 1 U-100 U.

See https://ucum.org/ucum

[ehafeza]

Here is the reply from Dr Bruce Goldberg with the supporting documents attached:

Dr. Goldberg: "" The statement below from one of the included references basically sums up the rationale:

"Since there are no internationally accepted calibration standards for allergen-specific IgE tests, a total IgE calibration curve is used to convert the units measured to be expressed as quantitative allergen-specific IgE antibody levels (Fig. 2): kUA/l (where “A” stands for “allergen-specific”, thereby distinguishing units from the internationally standardized kU/l=IU/ml for total IgE determination). To this end, a reference curve calibrated to the official WHO standard for total IgE (formerly WHO 75/502, currently WHO 11/234) is generated following each assay run according to the specifications of the manufacturers of these diagnostic products. The measurement signals thus obtained for allergen-specific IgE are then converted into the corresponding units (kUA/l) with the help of this total IgE reference curve (“heterologous” calibration). As part of this process, one assumes a comparable binding strength between the allergen (extract) and specific IgE or between the primary anti-IgE antibodies used for the reference curve and total IgE—a source of error to a certain extent, which nevertheless needs to be accepted for heterologous calibration and which can cause deviations of maximum 10 %”. "" IgE references .zip

[ehafeza]

The approved UNIT is represented as follows: k[UA]/l (k prefixable, not convertible)