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 56540-8: Glutamate decarboxylase 65 Ab IA Qn (S)

Name: LOINC Code 56540-8: Glutamate decarboxylase 65 Ab IA Qn (S)
Creator: HealthAssure Clinical Team
Published: 2026-05-21T08:59:38.263Z

56540-8 is a LOINC code used to identify Glutamate decarboxylase 65 Ab IA 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 Glutamate decarboxylase 65 Ab. 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 Glutamate decarboxylase 65 Ab. 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: IA

What it does not mean

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

Key facts

Glutamate decarboxylase 65 Ab [Units/volume] in Serum by Immunoassay
Glutamate decarboxylase 65 Ab
ABS; Aby; Antby; Anti; Antibodies; Antibody; Arbitrary concentration; Autoantibodies; Autoantibody; Autoimmune myelopathy; c707; EIA; ELFA; ELISA; Endocrine; Endocrinology; Enzyme immunoassay; GAD; GAD65; GAD-65; GADA; Glu; Glutamic acid; Glutamic acid decarboxylase-65; IAA; Insulin-Dependent Diabetes Mellitus; MEIA; Paraneoplastic neurological syndrome; Point in time; QNT; Quan; Quant; Quantitative; Random; Serology; Serum; SR; SUDS; UniversalLabOrders

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

Glutamate decarboxylase 65 Ab IA Qn (S)Glutamate decarboxylase 65 Ab [Units/volume] in Serum by ImmunoassayGAD65 Ab Ser IA-aCncGlutamate decarboxylase 65 AbSEROGlutamate decarboxylase 65 antibody, BloodACnc

Frequently asked questions

Code details

Code56540-8

SystemLOINC

Display nameGlutamate decarboxylase 65 Ab IA Qn (S)

DescriptionGlutamate decarboxylase 65 Ab

Short nameGAD65 Ab Ser IA-aCnc

ComponentGlutamate decarboxylase 65 Ab

PropertyACnc

TimingPt

System (specimen)Ser

ScaleQn

MethodIA

ClassSERO

Example unitsarb U/mL

StatusACTIVE

Order/ObservationBoth

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.29

Last changed2.73

Consumer names

Glutamate decarboxylase 65 antibody, Blood

Part names

Glutamate decarboxylase 65 AbACncPtSerQnIAArbitrary ConcentrationPoint in time (spot)SerumImmunoassay

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.