What does this LOINC code represent?

This LOINC code identifies a lab observation, measurement, question, or clinical concept in a standardized format.

Is this enough to understand my test result?

No. The code identifies the test or observation, but the interpretation depends on the actual result, reference range, and clinical context.

LOINCObservation

LOINC Code 21544-2: Sulfamethoxazole IgE RAST class (S)

Name: LOINC Code 21544-2: Sulfamethoxazole IgE RAST class (S)
Creator: HealthAssure Clinical Team
Published: 2026-05-21T11:17:29.463Z

21544-2 is a LOINC code used to identify Sulfamethoxazole IgE RAST class (S) in laboratory and clinical observation data. You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges. LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Sulfamethoxazole Ab.IgE.RAST class. It is commonly used with the system or sample type Ser.

Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026

What is this code?

LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Sulfamethoxazole Ab.IgE.RAST class. It is commonly used with the system or sample type Ser.

When is it used?

Used in lab systems, EHRs, and clinical data exchange.
May identify a test, observation, survey item, or clinical document request rather than a diagnosis.
Status: DEPRECATED
Order vs observation: Observation

What it does not mean

The code identifies the observation or test, not the actual result.

Key facts

Deprecated Sulfamethoxazole IgE Ab RAST class [Presence] in Serum
Sulfamethoxazole Ab.IgE.RAST class
ABS; Aby; Acetylsulfamethoxazole; Allergen; Allergens; ALLERGY TESTING; Antby; Anti; Antibodies; Antibody; Autoantibodies; Autoantibody; c203; c223; C61; Gantanol; IgE RAST; Immune globulin E; Immunoglobulin E; Ordinal; Point in time; PR; QL; Qual; Qualitative; Random; Screen; Serum; SMX; SR; Sulfa; Sulfamethox

Where you may see this code

You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges.

Common synonyms

Sulfamethoxazole IgE RAST class (S)Deprecated Sulfamethoxazole IgE Ab RAST class [Presence] in SerumDeprecated Sulfamethoxazole IgE RAST QlSulfamethoxazole Ab.IgE.RAST classALLERGYSulfamethoxazole allergy testPrThr

Frequently asked questions

Code details

Code21544-2

SystemLOINC

Display nameSulfamethoxazole IgE RAST class (S)

DescriptionSulfamethoxazole Ab.IgE.RAST class

Short nameDeprecated Sulfamethoxazole IgE RAST Ql

ComponentSulfamethoxazole Ab.IgE.RAST class

PropertyPrThr

TimingPt

System (specimen)Ser

ScaleOrd

ClassALLERGY

StatusDEPRECATED

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released1.0m

Last changed2.75

Consumer names

Sulfamethoxazole allergy test

Part names

Sulfamethoxazole Ab.IgE.RAST classPrThrPtSerOrdPresence or ThresholdPoint in time (spot)Serum

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from LOINC. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.