LOINCActiveBoth

LOINC Code 5299-3: Rheumatoid factor LA (S) [Titer]

5299-3 is a LOINC code used to identify Rheumatoid factor LA (S) [Titer] 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 Rheumatoid factor. It is commonly used with the system or sample type Ser.

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 Rheumatoid factor. 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: ACTIVE
  • Order vs observation: Both
  • Method: LA

What it does not mean

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

Key facts

  • Rheumatoid factor [Titer] in Serum by Latex agglutination
  • Rheumatoid factor
  • Dilution factor; Dilution Factor (Titer); Fac; Fact; LAT; Latex agglutination; Point in time; Random; RF; Rheum; Rheumatology; Serology; Serum; SmQn; SR; Titer; Titered; Titre; Ttr

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

Rheumatoid factor LA (S) [Titer]Rheumatoid factor [Titer] in Serum by Latex agglutinationRheumatoid fact Titr Ser LARheumatoid factorSERORheumatoid factor, BloodTitr

Frequently asked questions

Code details

Code5299-3
SystemLOINC
Display nameRheumatoid factor LA (S) [Titer]
DescriptionRheumatoid factor
Short nameRheumatoid fact Titr Ser LA
ComponentRheumatoid factor
PropertyTitr
TimingPt
System (specimen)Ser
ScaleSemiQn
MethodLA
ClassSERO
Example unitstiter
StatusACTIVE
Order/ObservationBoth

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released1.0
Last changed2.75

Consumer names

Rheumatoid factor, Blood

Part names

Rheumatoid factorTitrPtSerSemiQnLATiterPoint in time (spot)SerumLatex agglutination

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.

LOINC Code 5299-3 | HealthAssure