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 12952-8: T4 uptake 1 Hr post Unsp challenge [Mass/Vol]

Name: LOINC Code 12952-8: T4 uptake 1 Hr post Unsp challenge [Mass/Vol]
Creator: HealthAssure Clinical Team
Published: 2026-05-21T11:17:23.607Z

12952-8 is a LOINC code used to identify T4 uptake 1 Hr post Unsp challenge [Mass/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 Thyroxine uptake^1H 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 Thyroxine uptake^1H 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: DEPRECATED
Order vs observation: Observation

What it does not mean

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

Key facts

Deprecated Thyroxine (T4) uptake [Mass/volume] in Serum or Plasma --1 hour post XXX challenge
Thyroxine uptake^1H post XXX challenge
1 hour; 1.0Hr; 1h p chal; 60 min; 60 minutes; 60M; 60min; After; CHEMISTRY.CHALLENGE TESTING; Level; Levothyroxine; Levo-thyroxine; L-thyroxine; Mass concentration; p chal; Pl; Plasma; Plsm; Point in time; PST; QNT; Quan; Quant; Quantitative; Random; SerP; SerPl; SerPlas; Serum; Serum or plasma; SR; T4; T-4; T4U; thyroid hormone; Thyrox; Thyroxin; Thyrx; Total T4; TT4

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

T4 uptake 1 Hr post Unsp challenge [Mass/Vol]Deprecated Thyroxine (T4) uptake [Mass/volume] in Serum or Plasma --1 hour post XXX challengeDeprecated T4U 1h p chal SerPl-mCncThyroxine uptake^1H post XXX challengeCHALT4 uptake 1 hr after challenge, BloodMCnc

Frequently asked questions

Code details

Code12952-8

SystemLOINC

Display nameT4 uptake 1 Hr post Unsp challenge [Mass/Vol]

DescriptionThyroxine uptake^1H post XXX challenge

Short nameDeprecated T4U 1h p chal SerPl-mCnc

ComponentThyroxine uptake^1H post XXX challenge

PropertyMCnc

TimingPt

System (specimen)Ser/Plas

ScaleQn

ClassCHAL

StatusDEPRECATED

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released1.0j-a

Last changed2.48

Consumer names

T4 uptake 1 hr after challenge, Blood

Part names

Thyroxine uptake^1H post XXX challengeMCncPtSer/PlasQnMass 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.