LOINC

LOINC Code 4475-0: Complement C1 (P)

4475-0 is a LOINC code used to identify Complement C1 (P) 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 C1. It is commonly used with the system or sample type 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 Complement C1. It is commonly used with the system or sample type 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: DEPRECATED

What it does not mean

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

Key facts

  • Deprecated Complement C1
  • Complement C1
  • Comp; Complmt; HEMATOLOGY/CELL COUNTS; Pl; Plasma; Plsm; Point in time; QNT; Quan; Quant; Quantitative; Random

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 C1 (P)Deprecated Complement C1Deprecated C1 Plas QnComplement C1HEM/BCComplement C1, Blood-

Frequently asked questions

Code details

Code4475-0
SystemLOINC
Display nameComplement C1 (P)
DescriptionComplement C1
Short nameDeprecated C1 Plas Qn
ComponentComplement C1
Property-
TimingPt
System (specimen)Plas
ScaleQn
ClassHEM/BC
StatusDEPRECATED

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released1.0
Last changed2.66

Consumer names

Complement C1, Blood

Part names

Complement C1-PtPlasQnPoint in time (spot)Plasma

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 4475-0 | HealthAssure