LOINCActiveObservation

LOINC Code 20649-0: Leucine [Moles/Vol]

20649-0 is a LOINC code used to identify Leucine [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 Leucine. It is commonly used with the system or sample type Ser/Plas.

Reviewed by HealthAssure Clinical TeamUpdated 25 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 Leucine. 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

  • Leucine [Moles/volume] in Serum or Plasma
  • Leucine
  • Genetic metabolic specialist (from Canada) point out that plasma may be the traditional sample of choice, but they see no clinically significant difference between plasma and serum amino acids.
  • Chemistry; Leu; Level; Pl; Plasma; Plsm; Point in time; 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

Leucine [Moles/Vol]Leucine [Moles/volume] in Serum or PlasmaLeucine SerPl-sCncLeucineCHEMLeucine, BloodSCnc

Frequently asked questions

Code details

Code20649-0
SystemLOINC
Display nameLeucine [Moles/Vol]
DescriptionLeucine
Short nameLeucine SerPl-sCnc
ComponentLeucine
PropertySCnc
TimingPt
System (specimen)Ser/Plas
ScaleQn
ClassCHEM
Example unitsmcmol/dL; mcmol/L; umol/L
StatusACTIVE
Order/ObservationObservation

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released1.0m
Last changed2.73

Consumer names

Leucine, Blood

Part names

LeucineSCncPtSer/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.

LOINC Code 20649-0 | HealthAssure