LOINCActiveBoth

LOINC Code 53350-5: Free T4 (DBS) [Moles/Vol]

53350-5 is a LOINC code used to identify Free T4 (DBS) [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 Thyroxine.free. It is commonly used with the system or sample type Bld.dot.

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 Thyroxine.free. It is commonly used with the system or sample type Bld.dot.

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: Both

What it does not mean

  • The code identifies the observation or test, not the actual result.

Key facts

  • Thyroxine (T4) free [Moles/volume] in DBS
  • Thyroxine.free
  • Blood; Chemistry; DBS; Dried blood spot; Endocrine; Endocrinology; Filter paper; FP; FR; FreeT4; FT4; Level; Levothyroxine; Levo-thyroxine; L-thyroxine; Non-protein bound; Point in time; QNT; Quan; Quant; Quantitative; Random; Substance concentration; T4; T-4; T4 Free; thyroid hormone; Thyrox; Thyroxin; Thyrx; Total T4; TT4; WB; Whole blood

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

Free T4 (DBS) [Moles/Vol]Thyroxine (T4) free [Moles/volume] in DBST4 Free DBS-sCncThyroxine.freeCHEMFree T4, Dried blood spotSCnc

Frequently asked questions

Code details

Code53350-5
SystemLOINC
Display nameFree T4 (DBS) [Moles/Vol]
DescriptionThyroxine.free
Short nameT4 Free DBS-sCnc
ComponentThyroxine.free
PropertySCnc
TimingPt
System (specimen)Bld.dot
ScaleQn
ClassCHEM
Example unitsnmol/L
StatusACTIVE
Order/ObservationBoth

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released2.24
Last changed2.70

Consumer names

Free T4, Dried blood spot

Part names

Thyroxine.freeSCncPtBld.dotQnThyroxine freeSubstance ConcentrationPoint in time (spot)DBS

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 53350-5 | HealthAssure