LOINCActiveBoth

LOINC Code 48494-9: Complement C1 esterase inhibitor actual/normal [Rel catalytic activity/Vol]

48494-9 is a LOINC code used to identify Complement C1 esterase inhibitor actual/normal [Rel catalytic activity/Vol] 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 esterase inhibitor 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 C1 esterase inhibitor 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: Both

What it does not mean

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

Key facts

Complement C1 esterase inhibitor actual/normal in Serum or Plasma
Complement C1 esterase inhibitor actual/Normal
Functional C1 esterase inhibitor is reported as % means "percent of functional over mean normal" by many commonly used kits. This is reported by LOINC code 48494-9. Many sites have incorrectly mapped to [LOINC10634-4] (functional /Total) which is not the component reported by the commonly used methods.
Act/Nor; C1 inactivator; C1 inhibiting factor; C1INA; C1INH; C1-INH; Comp; Complmt; Control; HEMATOLOGY/CELL COUNTS; Inhib; Inhibit; Pl; Plasma; Plsm; Point in time; QNT; Quan; Quant; Quantitative; Random; RlCCnc; 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 C1 esterase inhibitor actual/normal [Rel catalytic activity/Vol]Complement C1 esterase inhibitor actual/normal in Serum or PlasmaC1INH Act/Nor SerPlComplement C1 esterase inhibitor actual/NormalHEM/BCComplement C1 Esterase Inhibitor actual/normal, BloodRelCCnc

Frequently asked questions

Code details

Code48494-9
SystemLOINC
Display nameComplement C1 esterase inhibitor actual/normal [Rel catalytic activity/Vol]
DescriptionComplement C1 esterase inhibitor actual/Normal
Short nameC1INH Act/Nor SerPl
ComponentComplement C1 esterase inhibitor actual/Normal
PropertyRelCCnc
TimingPt
System (specimen)Ser/Plas
ScaleQn
ClassHEM/BC
Example units%
StatusACTIVE
Order/ObservationBoth

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released2.21
Last changed2.73

Consumer names

Complement C1 Esterase Inhibitor actual/normal, Blood

Part names

Complement C1 esterase inhibitor actual/NormalRelCCncPtSer/PlasQnRelative catalytic 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 48494-9 | HealthAssure