What does this LOINC code represent?

This LOINC code identifies a lab observation, measurement, question, or clinical concept in a standardized format.

Is this enough to understand my test result?

No. The code identifies the test or observation, but the interpretation depends on the actual result, reference range, and clinical context.

LOINCActiveBoth

LOINC Code 53440-4: Argininosuccinate synthase (Liver fetus) [Catalytic activity/Mass]

Name: LOINC Code 53440-4: Argininosuccinate synthase (Liver fetus) [Catalytic activity/Mass]
Creator: HealthAssure Clinical Team
Published: 2026-05-21T08:59:36.030Z

53440-4 is a LOINC code used to identify Argininosuccinate synthase (Liver fetus) [Catalytic activity/Mass] 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 Argininosuccinate synthase. It is commonly used with the system or sample type Liver^Fetus.

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 Argininosuccinate synthase. It is commonly used with the system or sample type Liver^Fetus.

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

Argininosuccinate synthase [Enzymatic activity/mass] in Liver from Fetus
Argininosuccinate synthase
Argininosuccinic acid; arginosuccinate; Arginosuccinic acid; ASA; ASA Synthase; Catalytic Content; Chemistry; Fetal; Gyn; Gynecology; Hepar; Hepatic; OB; ObGyn; Obstetrics; 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

Argininosuccinate synthase (Liver fetus) [Catalytic activity/Mass]Argininosuccinate synthase [Enzymatic activity/mass] in Liver from FetusASA Synthase Liver Fetus-cCntArgininosuccinate synthaseCHEMFetal Argininosuccinate synthaseCCnt

Frequently asked questions

Code details

Code53440-4

SystemLOINC

Display nameArgininosuccinate synthase (Liver fetus) [Catalytic activity/Mass]

DescriptionArgininosuccinate synthase

Short nameASA Synthase Liver Fetus-cCnt

ComponentArgininosuccinate synthase

PropertyCCnt

TimingPt

System (specimen)Liver^Fetus

ScaleQn

ClassCHEM

Example unitsnmol/min/mg protein

StatusACTIVE

Order/ObservationBoth

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.26

Last changed2.70

Consumer names

Fetal Argininosuccinate synthase

Part names

Argininosuccinate synthaseCCntPtLiver^FetusQnCatalytic ContentPoint in time (spot)

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.