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LOINC Code 21121-9: B. hermsii IgG IF (S) [Titer]

21121-9 is a LOINC code used to identify B. hermsii IgG IF (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 Borrelia hermsii Ab.IgG. 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 Borrelia hermsii Ab.IgG. 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: IF

What it does not mean

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

Key facts

  • Borrelia hermsii IgG Ab [Titer] in Serum by Immunofluorescence
  • Borrelia hermsii Ab.IgG
  • ABS; Aby; ACIF; Antby; Anti; Antibodies; Antibody; Anticomplement Immunofluorescence; Autoantibodies; Autoantibody; B hermsii; Dilution factor; Dilution Factor (Titer); FA; Fluorescent antibody; Fluoresent; ID; IFA; Immune fluorescence; Immune globulin G; Immunoflour; Immunofluor; Immunofluorescence; Immunoglobulin G; Infectious Disease; InfectiousDisease; Microbiology; Point in time; Random; Relapsing fever; Serum; SmQn; SR; Time Resolved Fluorescence; Titer; Titered; Titre; TRF; 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

B. hermsii IgG IF (S) [Titer]Borrelia hermsii IgG Ab [Titer] in Serum by ImmunofluorescenceB hermsii IgG Titr Ser IFBorrelia hermsii Ab.IgGMICROBorrelia hermsii IgG antibody, BloodTitr

Frequently asked questions

Code details

Code21121-9
SystemLOINC
Display nameB. hermsii IgG IF (S) [Titer]
DescriptionBorrelia hermsii Ab.IgG
Short nameB hermsii IgG Titr Ser IF
ComponentBorrelia hermsii Ab.IgG
PropertyTitr
TimingPt
System (specimen)Ser
ScaleSemiQn
MethodIF
ClassMICRO
Example unitstiter
StatusACTIVE
Order/ObservationBoth

Flags

BillableNo
Valid clinical useNo

Source

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

Consumer names

Borrelia hermsii IgG antibody, Blood

Part names

Borrelia hermsii Ab.IgGTitrPtSerSemiQnIFBorrelia hermsii IgGTiterPoint in time (spot)SerumImmunofluorescence (IF)

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 21121-9 | HealthAssure