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LOINC Code 109634-6: Cytochrome B5 reductase (RBC) [Measurement]

109634-6 is a LOINC code used to identify Cytochrome B5 reductase (RBC) [Measurement] 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 Cytochrome b5 reductase. It is commonly used with the system or sample type RBC.

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 Cytochrome b5 reductase. It is commonly used with the system or sample type RBC.

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: TRIAL
  • Order vs observation: Order

What it does not mean

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

Key facts

Cytochrome B5 reductase [Measurement] in Red Blood Cells
Cytochrome b5 reductase
This term is intended to collate similar measurements for the LOINC SNOMED CT Collaboration in an ontological view. Additionally, it can be used to communicate a laboratory order, either alone or in combination with specimen or other information in the order. It may NOT be used to report back the measured patient value. [https//lo.inc/ce2mb6]
B5 Reductase, NADH-Cytochrome; CyB5 Reduct; cyt; Erythrocytes; Lab orders; Methemoglobin reductase; Msmt; NADH Cytochrome B5 Reductase; NADH Methemoglobin Reductase; NADH-Cytochrome B5 Reductase; Red blood cells; Red blood corpusles

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

Cytochrome B5 reductase (RBC) [Measurement]Cytochrome B5 reductase [Measurement] in Red Blood CellsCyB5 Reduct Msmt RBCCytochrome b5 reductaseLABORDERS.ONTOLOGYCytochrome B5 Reductase, Red blood cells{Measurement}

Frequently asked questions

Code details

Code109634-6
SystemLOINC
Display nameCytochrome B5 reductase (RBC) [Measurement]
DescriptionCytochrome b5 reductase
Short nameCyB5 Reduct Msmt RBC
ComponentCytochrome b5 reductase
Property{Measurement}
Timing-
System (specimen)RBC
Scale-
ClassLABORDERS.ONTOLOGY
StatusTRIAL
Order/ObservationOrder

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released2.81
Last changed2.81

Consumer names

Cytochrome B5 Reductase, Red blood cells

Part names

Cytochrome B5 reductase{Measurement}-RBCMeasurementRed 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.