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 90797-2: T4 2 Hr post dose levothyroxine [Mass/Vol]

Name: LOINC Code 90797-2: T4 2 Hr post dose levothyroxine [Mass/Vol]
Creator: HealthAssure Clinical Team
Published: 2026-05-21T09:00:20.875Z

90797-2 is a LOINC code used to identify T4 2 Hr post dose levothyroxine [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^2H post dose levothyroxine. 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^2H post dose levothyroxine. 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

Thyroxine (T4) [Mass/volume] in Serum or Plasma --2 hours post dose levothyroxine
Thyroxine^2H post dose levothyroxine
120 min; 120 minutes; 120min; 2 hours; 2h p levo; After; c99; CHEMISTRY.CHALLENGE TESTING; Endocrine; Endocrinology; Level; Levothyroxine; Levo-thyroxine; L-thyroxine; Mass concentration; p dose; Pl; Plasma; Plsm; Point in time; PST; QNT; Quan; Quant; Quantitative; Random; SerP; SerPl; SerPlas; Serum; Serum or plasma; SR; T4; T-4; 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 2 Hr post dose levothyroxine [Mass/Vol]Thyroxine (T4) [Mass/volume] in Serum or Plasma --2 hours post dose levothyroxineT4 2h p levo SerPl-mCncThyroxine^2H post dose levothyroxineCHALT4 2 hr after levothyroxine, BloodMCnc

Frequently asked questions

Code details

Code90797-2

SystemLOINC

Display nameT4 2 Hr post dose levothyroxine [Mass/Vol]

DescriptionThyroxine^2H post dose levothyroxine

Short nameT4 2h p levo SerPl-mCnc

ComponentThyroxine^2H post dose levothyroxine

PropertyMCnc

TimingPt

System (specimen)Ser/Plas

ScaleQn

ClassCHAL

Example unitsmcg/dL

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.65

Last changed2.65

Consumer names

T4 2 hr after levothyroxine, Blood

Part names

Thyroxine^2H post dose levothyroxineMCncPtSer/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.