LOINCActiveObservation

LOINC Code 33911-9: Complement C1r actual/normal [Relative mass conc]

33911-9 is a LOINC code used to identify Complement C1r actual/normal [Relative mass conc] 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 C1r actual/Normal. 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 Complement C1r actual/Normal. 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: Observation

What it does not mean

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

Key facts

  • Complement C1r actual/normal in Serum or Plasma
  • Complement C1r actual/Normal
  • Act/Nor; Comp; Complmt; Control; HEMATOLOGY/CELL COUNTS; Pl; Plasma; Plsm; Point in time; QNT; Quan; Quant; Quantitative; Random; Relative mass concentration; RLMCNC; SerP; SerPl; SerPlas; Serum; Serum or plasma; SR

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 C1r actual/normal [Relative mass conc]Complement C1r actual/normal in Serum or PlasmaC1r Act/Nor SerPlComplement C1r actual/NormalHEM/BCComplement C1r actual/normal, BloodRelMCnc

Frequently asked questions

Code details

Code33911-9
SystemLOINC
Display nameComplement C1r actual/normal [Relative mass conc]
DescriptionComplement C1r actual/Normal
Short nameC1r Act/Nor SerPl
ComponentComplement C1r actual/Normal
PropertyRelMCnc
TimingPt
System (specimen)Ser/Plas
ScaleQn
ClassHEM/BC
Example units%
StatusACTIVE
Order/ObservationObservation

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released2.09
Last changed2.73

Consumer names

Complement C1r actual/normal, Blood

Part names

Complement C1r actual/NormalRelMCncPtSer/PlasQnRelative Mass ConcentrationPoint in time (spot)Serum or 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 33911-9 | HealthAssure