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 12939-5: TSH 2 Hr post Unsp challenge Qn

Name: LOINC Code 12939-5: TSH 2 Hr post Unsp challenge Qn
Creator: HealthAssure Clinical Team
Published: 2026-05-21T11:17:23.607Z

12939-5 is a LOINC code used to identify TSH 2 Hr post Unsp challenge Qn 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 Thyrotropin^2H post XXX challenge. 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 Thyrotropin^2H post XXX challenge. 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: Observation

What it does not mean

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

Key facts

Thyrotropin [Units/volume] in Serum or Plasma --2 hours post XXX challenge
Thyrotropin^2H post XXX challenge
120 min; 120 minutes; 120min; 2 hours; 2h p chal; After; Arbitrary concentration; CHEMISTRY.CHALLENGE TESTING; Endocrine; Endocrinology; p chal; Pl; Plasma; Plsm; Point in time; PST; QNT; Quan; Quant; Quantitative; Random; SerP; SerPl; SerPlas; Serum; Serum or plasma; SR; Thyroid stimulating hormone; Thyrotropic hormone; TSH

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

TSH 2 Hr post Unsp challenge QnThyrotropin [Units/volume] in Serum or Plasma --2 hours post XXX challengeTSH 2h p chal SerPl-aCncThyrotropin^2H post XXX challengeCHALThyroid Stimulating Hormone (TSH; Thyrotropin) 2 hr after challenge, BloodACnc

Frequently asked questions

Code details

Code12939-5

SystemLOINC

Display nameTSH 2 Hr post Unsp challenge Qn

DescriptionThyrotropin^2H post XXX challenge

Short nameTSH 2h p chal SerPl-aCnc

ComponentThyrotropin^2H post XXX challenge

PropertyACnc

TimingPt

System (specimen)Ser/Plas

ScaleQn

ClassCHAL

Example unitsmIU/L;mcU/mL

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released1.0j-a

Last changed2.36

Consumer names

Thyroid Stimulating Hormone (TSH; Thyrotropin) 2 hr after challenge, Blood

Part names

Thyrotropin^2H post XXX challengeACncPtSer/PlasQnArbitrary 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.