LOINCActiveBoth

LOINC Code 1291-4: P1 Ag Ql (RBC)

1291-4 is a LOINC code used to identify P1 Ag Ql (RBC) 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 P1 Ag. It is commonly used with the system or sample type RBC.

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 P1 Ag. It is commonly used with the system or sample type RBC.

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

What it does not mean

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

Key facts

  • P1 Ag [Presence] on Red Blood Cells
  • P1 Ag
  • Antigen; Antigens; BLOOD BANK; 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

P1 Ag Ql (RBC)P1 Ag [Presence] on Red Blood CellsP1 Ag RBC QlP1 AgBLDBKP1 antigen, Red blood cellsPrThr

Frequently asked questions

Code details

Code1291-4
SystemLOINC
Display nameP1 Ag Ql (RBC)
DescriptionP1 Ag
Short nameP1 Ag RBC Ql
ComponentP1 Ag
PropertyPrThr
TimingPt
System (specimen)RBC
ScaleOrd
ClassBLDBK
StatusACTIVE
Order/ObservationBoth

Flags

BillableNo
Valid clinical useNo

Source

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

Consumer names

P1 antigen, Red blood cells

Part names

P1 AgPrThrPtRBCOrdPresence or ThresholdPoint in time (spot)Red Blood Cells

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 1291-4 | HealthAssure