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 56477-3: TPO Ab IA Qn

Name: LOINC Code 56477-3: TPO Ab IA Qn
Creator: HealthAssure Clinical Team
Published: 2026-05-21T08:59:38.260Z

56477-3 is a LOINC code used to identify TPO Ab IA Qn 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 Thyroperoxidase Ab. It is commonly used with the system or sample type Ser/Plas.

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 Thyroperoxidase Ab. It is commonly used with the system or sample type Ser/Plas.

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

Thyroperoxidase Ab [Units/volume] in Serum or Plasma by Immunoassay
Thyroperoxidase Ab
ABS; Aby; Antby; Anti; Antibodies; Antibody; Arbitrary concentration; Autoantibodies; Autoantibody; EIA; ELFA; ELISA; Endocrine; Endocrinology; Enzyme immunoassay; IAA; Iodide peroxidase; MEIA; Pl; Plasma; Plsm; Point in time; QNT; Quan; Quant; Quantitative; Random; Serology; SerP; SerPl; SerPlas; Serum; Serum or plasma; SR; SUDS; Thyroid Microsomal; Thyroid microsomes; Thyroid peroxidase; TPO

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

TPO Ab IA QnThyroperoxidase Ab [Units/volume] in Serum or Plasma by ImmunoassayThyroperoxidase Ab SerPl IA-aCncThyroperoxidase AbSEROTPO antibody, BloodACnc

Frequently asked questions

Code details

Code56477-3

SystemLOINC

Display nameTPO Ab IA Qn

DescriptionThyroperoxidase Ab

Short nameThyroperoxidase Ab SerPl IA-aCnc

ComponentThyroperoxidase Ab

PropertyACnc

TimingPt

System (specimen)Ser/Plas

ScaleQn

MethodIA

ClassSERO

Example unitsindex

StatusACTIVE

Order/ObservationBoth

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.29

Last changed2.73

Consumer names

TPO antibody, Blood

Part names

Thyroperoxidase AbACncPtSer/PlasQnIAArbitrary ConcentrationPoint in time (spot)Serum or PlasmaImmunoassay

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.