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LOINC Code 10548-6: Phenytoin Free/Total phenytoin [Mass fraction]

10548-6 is a LOINC code used to identify Phenytoin Free/Total phenytoin [Mass fraction] 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 Phenytoin.free/Phenytoin.total. 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 Phenytoin.free/Phenytoin.total. 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

  • Phenytoin Free/Phenytoin.total in Serum or Plasma
  • Phenytoin.free/Phenytoin.total
  • DI-HYDAN; Dilantin; Dilj; Diphenylhydantoin; DPH; DRUG/TOXICOLOGY; Drugs; Epanutin; Fenantoin; FR; Lehydan; Mass fraction; Non-protein bound; Percent; Phenhydan; Phenytoin Free; Phenytoin Total; PHYT; Pl; Plasma; Plsm; Point in time; QNT; Quan; Quant; Quantitative; Random; SerP; SerPl; SerPlas; Serum; Serum or plasma; Sinergina; SR; Tot; Totl; Zentropil

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

Phenytoin Free/Total phenytoin [Mass fraction]Phenytoin Free/Phenytoin.total in Serum or PlasmaPhenytoin Free MFr SerPlPhenytoin.free/Phenytoin.totalDRUG/TOXFree phenytoin/Phenytoin.total, BloodMFr

Frequently asked questions

Code details

Code10548-6
SystemLOINC
Display namePhenytoin Free/Total phenytoin [Mass fraction]
DescriptionPhenytoin.free/Phenytoin.total
Short namePhenytoin Free MFr SerPl
ComponentPhenytoin.free/Phenytoin.total
PropertyMFr
TimingPt
System (specimen)Ser/Plas
ScaleQn
ClassDRUG/TOX
Example units%
StatusACTIVE
Order/ObservationObservation

Flags

BillableNo
Valid clinical useNo

Source

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

Consumer names

Free phenytoin/Phenytoin.total, Blood

Part names

Phenytoin.free/Phenytoin.totalMFrPtSer/PlasQnMass fractionPoint 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.