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 98990-5: Methotrexate 18 Hr post dose [Moles/Vol]

Name: LOINC Code 98990-5: Methotrexate 18 Hr post dose [Moles/Vol]
Creator: HealthAssure Clinical Team
Published: 2026-05-21T09:00:33.064Z

98990-5 is a LOINC code used to identify Methotrexate 18 Hr post dose [Moles/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 Methotrexate^18H post dose. 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 Methotrexate^18H post dose. 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

Methotrexate [Moles/volume] in Serum or Plasma --18 hour post dose
Methotrexate^18H post dose
After; Amethoperin; Amethopterin; DRUG/TOXICOLOGY; Drugs; Level; Methotrexat; MTX; p dose; Pl; Plasma; Plsm; Point in time; PST; QNT; Quan; Quant; Quantitative; Random; SerP; SerPl; SerPlas; Serum; Serum or plasma; SR; Substance concentration

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

Methotrexate 18 Hr post dose [Moles/Vol]Methotrexate [Moles/volume] in Serum or Plasma --18 hour post doseMTX 18h p SerPl-sCncMethotrexate^18H post doseDRUG/TOXMethotrexate 18 hr after dose, BloodSCnc

Frequently asked questions

Code details

Code98990-5

SystemLOINC

Display nameMethotrexate 18 Hr post dose [Moles/Vol]

DescriptionMethotrexate^18H post dose

Short nameMTX 18h p SerPl-sCnc

ComponentMethotrexate^18H post dose

PropertySCnc

TimingPt

System (specimen)Ser/Plas

ScaleQn

ClassDRUG/TOX

Example unitsumol/L

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.72

Last changed2.72

Consumer names

Methotrexate 18 hr after dose, Blood

Part names

Methotrexate^18H post doseSCncPtSer/PlasQnSubstance 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.