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 5565-7: Terminal deoxyribonucleotidyl transferase Qn (WBC)

Name: LOINC Code 5565-7: Terminal deoxyribonucleotidyl transferase Qn (WBC)
Creator: HealthAssure Clinical Team
Published: 2026-05-25T17:13:11.347Z

5565-7 is a LOINC code used to identify Terminal deoxyribonucleotidyl transferase Qn (WBC) 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 Terminal deoxyribonucleotidyl transferase. It is commonly used with the system or sample type WBC.

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 Terminal deoxyribonucleotidyl transferase. It is commonly used with the system or sample type WBC.

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

Terminal deoxyribonucleotidyl transferase [Units/volume] in Leukocytes
Terminal deoxyribonucleotidyl transferase
Arbitrary concentration; CELL MARKERS; Leukocytes; Point in time; QNT; Quan; Quant; Quantitative; Random; TdT; WBCs; White blood cells

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.

Related SNOMED CT concepts

705114005SNOMED CT mapping for Terminal deoxyribonucleotidyl transferase Qn (WBC) (5565-7)

Related observations and tests

SNOMED_CT 705114005high

LOINC Code System

Source: LOINC-SNOMED cooperation package

Common synonyms

Terminal deoxyribonucleotidyl transferase Qn (WBC)Terminal deoxyribonucleotidyl transferase [Units/volume] in LeukocytesTdT WBC-aCncTerminal deoxyribonucleotidyl transferaseCELLMARKTerminal deoxyribonucleotidyl transferase, White blood cellsACnc

Frequently asked questions

Code details

Code5565-7

SystemLOINC

Display nameTerminal deoxyribonucleotidyl transferase Qn (WBC)

DescriptionTerminal deoxyribonucleotidyl transferase

Short nameTdT WBC-aCnc

ComponentTerminal deoxyribonucleotidyl transferase

PropertyACnc

TimingPt

System (specimen)WBC

ScaleQn

ClassCELLMARK

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released1.0

Last changed2.69

Consumer names

Terminal deoxyribonucleotidyl transferase, White blood cells

Part names

Terminal deoxyribonucleotidyl transferaseACncPtWBCQnArbitrary ConcentrationPoint in time (spot)White blood cells

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.