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 56900-4: Terminal deoxyribonucleotidyl transferase cells/Cells FC (CSF)

Name: LOINC Code 56900-4: Terminal deoxyribonucleotidyl transferase cells/Cells FC (CSF)
Creator: HealthAssure Clinical Team
Published: 2026-05-21T08:59:38.264Z

56900-4 is a LOINC code used to identify Terminal deoxyribonucleotidyl transferase cells/Cells FC (CSF) 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 Cells.terminal deoxyribonucleotidyl transferase/Cells. It is commonly used with the system or sample type CSF.

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 Cells.terminal deoxyribonucleotidyl transferase/Cells. It is commonly used with the system or sample type CSF.

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
Method: Flow cytometry

What it does not mean

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

Key facts

Terminal deoxyribonucleotidyl transferase cells/cells in Cerebral spinal fluid by Flow cytometry (FC)
Cells.terminal deoxyribonucleotidyl transferase/Cells
Cell; CELL MARKERS; Cellularity; Cerebral spinal fluid; Cerebrospinal Fl; Dynamic; FC; Number Fraction; Percent; Point in time; QNT; Quan; Quant; Quantitative; Random; Spinal Fl; Spinal Fld; Spinal Flu; Spinal Fluid; TdT; TdT 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.

Common synonyms

Terminal deoxyribonucleotidyl transferase cells/Cells FC (CSF)Terminal deoxyribonucleotidyl transferase cells/cells in Cerebral spinal fluid by Flow cytometry (FC)TdT Cells NFr CSF FCCells.terminal deoxyribonucleotidyl transferase/CellsCELLMARKTerminal deoxyribonucleotidyl transferase cells/cells, Spinal fluidNFr

Frequently asked questions

Code details

Code56900-4

SystemLOINC

Display nameTerminal deoxyribonucleotidyl transferase cells/Cells FC (CSF)

DescriptionCells.terminal deoxyribonucleotidyl transferase/Cells

Short nameTdT Cells NFr CSF FC

ComponentCells.terminal deoxyribonucleotidyl transferase/Cells

PropertyNFr

TimingPt

System (specimen)CSF

ScaleQn

MethodFlow cytometry

ClassCELLMARK

Example units%

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.29

Last changed2.79

Consumer names

Terminal deoxyribonucleotidyl transferase cells/cells, Spinal fluid

Part names

Cells.terminal deoxyribonucleotidyl transferase/CellsNFrPtCSFQnFlow cytometryNumber FractionPoint in time (spot)Cerebral spinal fluidFlow cytometry (FC)

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.