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.

LOINCActiveObservation

LOINC Code 91142-0: Thiopurine methyltransferase production of 6-MMP riboside (RBC) [Catalytic activity/Vol]

Name: LOINC Code 91142-0: Thiopurine methyltransferase production of 6-MMP riboside (RBC) [Catalytic activity/Vol]
Creator: HealthAssure Clinical Team
Published: 2026-05-21T09:00:20.876Z

91142-0 is a LOINC code used to identify Thiopurine methyltransferase production of 6-MMP riboside (RBC) [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 Thiopurine methyltransferase. It is commonly used with the system or sample type RBC.

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 Thiopurine methyltransferase. It is commonly used with the system or sample type RBC.

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: Production of 6-Methylmercaptopurine riboside

What it does not mean

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

Key facts

TPMT activity in RBC by production of 6-MMP riboside
Thiopurine methyltransferase
Catalytic Concentration; Chemistry; Erythrocytes; Methyl transferase; Point in time; production of 6-MMP; production of 6-MMP riboside; QNT; Quan; Quant; Quantitative; Random; Red blood cells; Red blood corpusles; TPMT

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

Thiopurine methyltransferase production of 6-MMP riboside (RBC) [Catalytic activity/Vol]TPMT activity in RBC by production of 6-MMP ribosideTPMT RBC production 6-MMP riboside-cCncThiopurine methyltransferaseCHEMThiopurine methyltransferase, Red blood cellsCCnc

Frequently asked questions

Code details

Code91142-0

SystemLOINC

Display nameThiopurine methyltransferase production of 6-MMP riboside (RBC) [Catalytic activity/Vol]

DescriptionThiopurine methyltransferase

Short nameTPMT RBC production 6-MMP riboside-cCnc

ComponentThiopurine methyltransferase

PropertyCCnc

TimingPt

System (specimen)RBC

ScaleQn

MethodProduction of 6-Methylmercaptopurine riboside

ClassCHEM

Example unitsnmol/mL/h

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.65

Last changed2.65

Consumer names

Thiopurine methyltransferase, Red blood cells

Part names

Thiopurine methyltransferaseCCncPtRBCQnProduction of 6-Methylmercaptopurine ribosideCatalytic ConcentrationPoint in time (spot)Red Blood Cells

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.