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 16521-7: Calcium 3rd specimen post Unsp challenge (U) [Moles/Vol]

Name: LOINC Code 16521-7: Calcium 3rd specimen post Unsp challenge (U) [Moles/Vol]
Creator: HealthAssure Clinical Team
Published: 2026-05-21T11:17:26.378Z

16521-7 is a LOINC code used to identify Calcium 3rd specimen post Unsp challenge (U) [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 Calcium^3rd specimen post XXX challenge. It is commonly used with the system or sample type Urine.

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 Calcium^3rd specimen post XXX challenge. It is commonly used with the system or sample type Urine.

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

Calcium [Moles/volume] in Urine --3rd specimen post XXX challenge
Calcium^3rd specimen post XXX challenge
After; Ca; Cal; CHEMISTRY.CHALLENGE TESTING; Level; p chal; Point in time; PST; QNT; Quan; Quant; Quantitative; Random; sp3; sp3 p chal; Spec; Substance concentration; UA; UR; Urn

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

Calcium 3rd specimen post Unsp challenge (U) [Moles/Vol]Calcium [Moles/volume] in Urine --3rd specimen post XXX challengeCalcium sp3 p chal Ur-sCncCalcium^3rd specimen post XXX challengeCHALCalcium 3rd specimen after challenge, UrineSCnc

Frequently asked questions

Code details

Code16521-7

SystemLOINC

Display nameCalcium 3rd specimen post Unsp challenge (U) [Moles/Vol]

DescriptionCalcium^3rd specimen post XXX challenge

Short nameCalcium sp3 p chal Ur-sCnc

ComponentCalcium^3rd specimen post XXX challenge

PropertySCnc

TimingPt

System (specimen)Urine

ScaleQn

ClassCHAL

Example unitsmmol/L

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released1.0l

Last changed2.34

Consumer names

Calcium 3rd specimen after challenge, Urine

Part names

Calcium^3rd specimen post XXX challengeSCncPtUrineQnSubstance 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.