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.

LOINCActiveBoth

LOINC Code 55900-5: Immunoglobulin light chains.free Immunofixation Ql (U)

Name: LOINC Code 55900-5: Immunoglobulin light chains.free Immunofixation Ql (U)
Creator: HealthAssure Clinical Team
Published: 2026-05-25T17:13:11.347Z

55900-5 is a LOINC code used to identify Immunoglobulin light chains.free Immunofixation Ql (U) 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 Immunoglobulin light chains.free. It is commonly used with the system or sample type Urine.

Reviewed by HealthAssure Clinical TeamUpdated 25 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 Immunoglobulin light chains.free. It is commonly used with the system or sample type Urine.

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: ACTIVE
Order vs observation: Both
Method: Immunofixation

What it does not mean

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

Key facts

Immunoglobulin light chains.free [Presence] in Urine by Immunofixation
Immunoglobulin light chains.free
Bence Jones protein; BJ Protein; BJ Protein Free; BJP; Chain; Chemistry; FLC; FR; Hematology; Heme; IFE; Ifix; Immune globulin; Immuno; Immunofixation electrophoresis; Immunoglob; Immunoglobin; Imunoglbon; Imunoglobn; Non-protein bound; Ordinal; Point in time; PR; QL; Qual; Qualitative; Random; Screen; UA; UR; Urn

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.

Related SNOMED CT concepts

705114005SNOMED CT mapping for Immunoglobulin light chains.free Immunofixation Ql (U) (55900-5)

Related observations and tests

SNOMED_CT 705114005high

LOINC Code System

Source: LOINC-SNOMED cooperation package

Common synonyms

Immunoglobulin light chains.free Immunofixation Ql (U)Immunoglobulin light chains.free [Presence] in Urine by ImmunofixationBJ Protein Free Ur Ql IFEImmunoglobulin light chains.freeCHEMFree light chains, UrinePrThr

Frequently asked questions

Code details

Code55900-5

SystemLOINC

Display nameImmunoglobulin light chains.free Immunofixation Ql (U)

DescriptionImmunoglobulin light chains.free

Short nameBJ Protein Free Ur Ql IFE

ComponentImmunoglobulin light chains.free

PropertyPrThr

TimingPt

System (specimen)Urine

ScaleOrd

MethodImmunofixation

ClassCHEM

StatusACTIVE

Order/ObservationBoth

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.29

Last changed2.73

Consumer names

Free light chains, Urine

Part names

Immunoglobulin light chains.freePrThrPtUrineOrdImmunofixationPresence or ThresholdPoint in time (spot)

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.