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 31644-8: S. pneumoniae 4 IgG spec 2 Qn (S)

Name: LOINC Code 31644-8: S. pneumoniae 4 IgG spec 2 Qn (S)
Creator: HealthAssure Clinical Team
Published: 2026-05-21T08:59:17.664Z

31644-8 is a LOINC code used to identify S. pneumoniae 4 IgG spec 2 Qn (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 Streptococcus pneumoniae 4 Ab.IgG^2nd specimen. 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 Streptococcus pneumoniae 4 Ab.IgG^2nd specimen. 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 Streptococcus pneumoniae 4 IgG Ab [Units/volume] in Serum --2nd specimen
Streptococcus pneumoniae 4 Ab.IgG^2nd specimen
ABS; Aby; Antby; Anti; Antibodies; Antibody; Arbitrary concentration; Autoantibodies; Autoantibody; Convalescent; ID; Immune globulin G; Immunoglobulin G; Infectious Disease; InfectiousDisease; Microbiology; Pneu; pneum; Pneumo; Pneumococ; Pneumococcal; Pneumococcal pneumonia; Pneumococcus; Pneumon; Pneumonia; Point in time; Post immunization; QNT; Quan; Quant; Quantitative; Random; S pneum4; S pneumo; S pneumoniae; Second; Serum; sp2; Spec; Spn; SR; Strep; Strept

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

S. pneumoniae 4 IgG spec 2 Qn (S)Deprecated Streptococcus pneumoniae 4 IgG Ab [Units/volume] in Serum --2nd specimenDeprecated S pneum4 IgG sp2 Ser-aCncStreptococcus pneumoniae 4 Ab.IgG^2nd specimenMICROStreptococcus pneumoniae 4 IgG antibody specimen 2, BloodACnc

Frequently asked questions

Code details

Code31644-8

SystemLOINC

Display nameS. pneumoniae 4 IgG spec 2 Qn (S)

DescriptionStreptococcus pneumoniae 4 Ab.IgG^2nd specimen

Short nameDeprecated S pneum4 IgG sp2 Ser-aCnc

ComponentStreptococcus pneumoniae 4 Ab.IgG^2nd specimen

PropertyACnc

TimingPt

System (specimen)Ser

ScaleQn

ClassMICRO

StatusDEPRECATED

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.07

Last changed2.69

Consumer names

Streptococcus pneumoniae 4 IgG antibody specimen 2, Blood

Part names

Streptococcus pneumoniae 4 Ab.IgG^2nd specimenACncPtSerQnArbitrary ConcentrationPoint 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.