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 55503-7: Prolactin 40 Min post dose TRH IV [Mass/Vol]

Name: LOINC Code 55503-7: Prolactin 40 Min post dose TRH IV [Mass/Vol]
Creator: HealthAssure Clinical Team
Published: 2026-05-21T08:59:37.765Z

55503-7 is a LOINC code used to identify Prolactin 40 Min post dose TRH IV [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 Prolactin^40M post dose TRH IV. 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 Prolactin^40M post dose TRH IV. 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

Prolactin [Mass/volume] in Serum or Plasma --40 minutes post dose TRH IV
Prolactin^40M post dose TRH IV
40M p TRH IV; After; CHEMISTRY.CHALLENGE TESTING; Lactotropic hormone; Lactotropin; Level; Mammatropic hormone; Mammotropin; Mass concentration; p dose; p TRH; Pl; Plasma; Plsm; Point in time; PRL; Prol; PST; QNT; Quan; Quant; Quantitative; Random; SerP; SerPl; SerPlas; Serum; Serum or plasma; SR

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

Prolactin 40 Min post dose TRH IV [Mass/Vol]Prolactin [Mass/volume] in Serum or Plasma --40 minutes post dose TRH IVProlactin 40M p TRH IV SerPl-mCncProlactin^40M post dose TRH IVCHALProlactin 40 min after TRH intravenous, BloodMCnc

Frequently asked questions

Code details

Code55503-7

SystemLOINC

Display nameProlactin 40 Min post dose TRH IV [Mass/Vol]

DescriptionProlactin^40M post dose TRH IV

Short nameProlactin 40M p TRH IV SerPl-mCnc

ComponentProlactin^40M post dose TRH IV

PropertyMCnc

TimingPt

System (specimen)Ser/Plas

ScaleQn

ClassCHAL

Example unitsng/mL;ug/L

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.27

Last changed2.40

Consumer names

Prolactin 40 min after TRH intravenous, Blood

Part names

Prolactin^40M post dose TRH IVMCncPtSer/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.