LOINCActiveObservation

LOINC Code 866-4: A3 Ag Ql (RBC BPU)

866-4 is a LOINC code used to identify A3 Ag Ql (RBC BPU) 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 A3 Ag. It is commonly used with the system or sample type RBC^BPU.

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 A3 Ag. It is commonly used with the system or sample type RBC^BPU.

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: Observation

What it does not mean

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

Key facts

  • A3 Ag [Presence] on Red Blood Cells from Blood product unit
  • A3 Ag
  • Antigen; Antigens; BLOOD BANK; Blood product unit; Blood Product Unit (Pack); Erythrocytes; Hematology; Heme; Ordinal; Point in time; PR; QL; Qual; Qualitative; Random; Red blood cells; Red blood corpusles; Screen

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

A3 Ag Ql (RBC BPU)A3 Ag [Presence] on Red Blood Cells from Blood product unitA3 Ag RBC BPU QlA3 AgBLDBKA3 antigen, Blood Product UnitPrThr

Frequently asked questions

Code details

Code866-4
SystemLOINC
Display nameA3 Ag Ql (RBC BPU)
DescriptionA3 Ag
Short nameA3 Ag RBC BPU Ql
ComponentA3 Ag
PropertyPrThr
TimingPt
System (specimen)RBC^BPU
ScaleOrd
ClassBLDBK
StatusACTIVE
Order/ObservationObservation

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released1.0
Last changed2.56

Consumer names

A3 antigen, Blood Product Unit

Part names

A3 AgPrThrPtRBC^BPUOrdPresence or ThresholdPoint in time (spot)

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 866-4 | HealthAssure