LOINCActiveBoth

LOINC Code 4504-7: Complement C4d (RBC) [Entitic number]

4504-7 is a LOINC code used to identify Complement C4d (RBC) [Entitic number] 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 Complement C4d. 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 Complement C4d. 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

  • Complement C4d [Entitic number] in Red Blood Cells
  • Complement C4d
  • Comp; Complmt; Entitic; Entitic number; Erythrocytes; HEMATOLOGY/CELL COUNTS; Point in time; QNT; Quan; Quant; Quantitative; Random; Red blood cells; Red blood corpusles

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

Complement C4d (RBC) [Entitic number]Complement C4d [Entitic number] in Red Blood CellsC4d EntNum RBCComplement C4dHEM/BCComplement C4d, Red blood cellsEntNum

Frequently asked questions

Code details

Code4504-7
SystemLOINC
Display nameComplement C4d (RBC) [Entitic number]
DescriptionComplement C4d
Short nameC4d EntNum RBC
ComponentComplement C4d
PropertyEntNum
TimingPt
System (specimen)RBC
ScaleQn
ClassHEM/BC
StatusACTIVE
Order/ObservationBoth

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released1.0
Last changed2.26

Consumer names

Complement C4d, Red blood cells

Part names

Complement C4dEntNumPtRBCQnEntitic numberPoint 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 4504-7 | HealthAssure