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LOINC Code 91120-6: Antithrombin Chromo.no addition of heparin (PPP) [Rel catalytic activity/Vol]

91120-6 is a LOINC code used to identify Antithrombin Chromo.no addition of heparin (PPP) [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 Antithrombin. It is commonly used with the system or sample type PPP.

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 Antithrombin. It is commonly used with the system or sample type PPP.

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
  • Method: Chromo.no addition of heparin

What it does not mean

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

Key facts

Antithrombin in Platelet poor plasma by Chromo.no addition of heparin
Antithrombin
This term represents an antithrombin (AT) assay which, in contrast to typical AT assays, is performed in the ABSENCE of heparin. This assay is also known as "Progressive antithrombin assay." It is used to identify type IIb AT deficiency, which is caused by a mutation in the AT heparin binding site (HBS). In type IIb AT deficiency, AT activity is reduced in the presence of heparin but is normal in the absence of heparin.[PMID19141163] This term was created for, but is not limited in use to, the Biophen Antithrombin 5 assay's VARIANT Method, which is performed without heparin. In patients with type IIb AT deficiency, AT activity is expected to be normal in patients with an HBS mutation.
Anti thrombin; Antithrm; Antithrombin III; Antithrombn; Anti-Xa; AT; AT III; ATIII; Chromo.no added heparin; Chromogenic assay; COAGULATION; ENZY; Enzymatic assay; Hematology; Heme; Heparin cofactor I; Plas; Platelet poor plasma; Point in time; QNT; Quan; Quant; Quantitative; Random; RlCCnc; Thrombin inhibitor I

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

Antithrombin Chromo.no addition of heparin (PPP) [Rel catalytic activity/Vol]Antithrombin in Platelet poor plasma by Chromo.no addition of heparinAT III PPP Chromo.no added heparinAntithrombinCOAGAntithrombin, BloodRelCCnc

Frequently asked questions

Code details

Code91120-6
SystemLOINC
Display nameAntithrombin Chromo.no addition of heparin (PPP) [Rel catalytic activity/Vol]
DescriptionAntithrombin
Short nameAT III PPP Chromo.no added heparin
ComponentAntithrombin
PropertyRelCCnc
TimingPt
System (specimen)PPP
ScaleQn
MethodChromo.no addition of heparin
ClassCOAG
Example units%
StatusACTIVE
Order/ObservationObservation

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released2.65
Last changed2.65

Consumer names

Antithrombin, Blood

Part names

AntithrombinRelCCncPtPPPQnChromo.no addition of heparinRelative catalytic concentrationPoint in time (spot)Platelet poor 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.