LOINC

LOINC Code 65643-9: Relative humidity

65643-9 is a LOINC code used to identify Relative humidity 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 Relative humidity. It is commonly used with the system or sample type Air.

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 Relative humidity. It is commonly used with the system or sample type Air.

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

What it does not mean

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

Key facts

  • Relative humidity
  • PhenX; Point in time; QNT; Quan; Quant; Quantitative; Random; Rel; Relative mass concentration; RLMCNC

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

Relative humidityPHENXRelMCncPtAirQnRelative Mass Concentration

Frequently asked questions

Code details

Code65643-9
SystemLOINC
Display nameRelative humidity
Short nameRelative humidity
ComponentRelative humidity
PropertyRelMCnc
TimingPt
System (specimen)Air
ScaleQn
ClassPHENX
Example units%
StatusTRIAL

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released2.36
Last changed2.65

Part names

Relative humidityRelMCncPtAirQnRelative Mass ConcentrationPoint in time (spot)

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 65643-9 | HealthAssure