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.

LOINCObservation

LOINC Code 42649-4: Isoniazid 0.2 ug/mL Slow-growing Mycobacteria [Susc]

Name: LOINC Code 42649-4: Isoniazid 0.2 ug/mL Slow-growing Mycobacteria [Susc]
Creator: HealthAssure Clinical Team
Published: 2026-05-21T08:59:28.128Z

42649-4 is a LOINC code used to identify Isoniazid 0.2 ug/mL Slow-growing Mycobacteria [Susc] 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 Isoniazid 0.2 ug/mL. It is commonly used with the system or sample type Isolate.

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 Isoniazid 0.2 ug/mL. It is commonly used with the system or sample type Isolate.

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: DEPRECATED
Order vs observation: Observation
Method: Slow-growing Mycobacteria

What it does not mean

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

Key facts

Deprecated Isoniazid 0.2 ug/mL [Susceptibility] by Method for Slow-growing mycobacteria
Isoniazid 0.2 ug/mL
ANTIBIOTIC SUSCEPTIBILITIES; AST; Hyzyd; ID; Infectious Disease; InfectiousDisease; INH; Islt; Isol; Isoniaz; Isoniazide; mcg; Nudrazod; Point in time; Random; Sus; Suscept; Susceptibilities; Susceptibility; Susceptibilty

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

Isoniazid 0.2 ug/mL Slow-growing Mycobacteria [Susc]Deprecated Isoniazid 0.2 ug/mL [Susceptibility] by Method for Slow-growing mycobacteriaDeprecated Isoniazid 0.2 ug/mL Islt SlowIsoniazid 0.2 ug/mLABXBACTSusceptibility to Isoniazid 0.2 ug/mLSusc

Frequently asked questions

Code details

Code42649-4

SystemLOINC

Display nameIsoniazid 0.2 ug/mL Slow-growing Mycobacteria [Susc]

DescriptionIsoniazid 0.2 ug/mL

Short nameDeprecated Isoniazid 0.2 ug/mL Islt Slow

ComponentIsoniazid 0.2 ug/mL

PropertySusc

TimingPt

System (specimen)Isolate

ScaleOrdQn

MethodSlow-growing Mycobacteria

ClassABXBACT

StatusDEPRECATED

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.16

Last changed2.36

Consumer names

Susceptibility to Isoniazid 0.2 ug/mL

Part names

Isoniazid 0.2 ug/mLSuscPtIsolateOrdQnSlow-growing MycobacteriaSusceptibility (microorganisms)Point 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.