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 53428-9: Fibroblast growth factor 23 3rd specimen post Unsp challenge IA Qn (P)

Name: LOINC Code 53428-9: Fibroblast growth factor 23 3rd specimen post Unsp challenge IA Qn (P)
Creator: HealthAssure Clinical Team
Published: 2026-05-21T08:59:36.030Z

53428-9 is a LOINC code used to identify Fibroblast growth factor 23 3rd specimen post Unsp challenge IA Qn (P) 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 Fibroblast growth factor 23 ^3rd specimen post XXX challenge. It is commonly used with the system or sample type Plas.

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 Fibroblast growth factor 23 ^3rd specimen post XXX challenge. It is commonly used with the system or sample type Plas.

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: IA

What it does not mean

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

Key facts

Fibroblast growth factor 23 [Units/volume] in Plasma by Immunoassay --3rd specimen post XXX challenge
Fibroblast growth factor 23 ^3rd specimen post XXX challenge
After; Arbitrary concentration; Autosomal dominant hypophosphatemic rickets; CHEMISTRY.CHALLENGE TESTING; EIA; ELFA; ELISA; Enzyme immunoassay; Fac; Fact; Familial tumoral calcinosis with hyperphosphatemia; FGF 23; FGF23; FGF-23; IAA; MEIA; p chal; Pl; Plasma; Plsm; Point in time; PST; QNT; Quan; Quant; Quantitative; Random; sp3; sp3 p chal; Spec; SUDS

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

Fibroblast growth factor 23 3rd specimen post Unsp challenge IA Qn (P)Fibroblast growth factor 23 [Units/volume] in Plasma by Immunoassay --3rd specimen post XXX challengeFGF-23 sp3 p chal Plas IA-aCncFibroblast growth factor 23 ^3rd specimen post XXX challengeCHALFibroblast growth factor 23 3rd specimen after challenge, BloodACnc

Frequently asked questions

Code details

Code53428-9

SystemLOINC

Display nameFibroblast growth factor 23 3rd specimen post Unsp challenge IA Qn (P)

DescriptionFibroblast growth factor 23 ^3rd specimen post XXX challenge

Short nameFGF-23 sp3 p chal Plas IA-aCnc

ComponentFibroblast growth factor 23 ^3rd specimen post XXX challenge

PropertyACnc

TimingPt

System (specimen)Plas

ScaleQn

MethodIA

ClassCHAL

Example unitsarb U/mL

StatusACTIVE

Order/ObservationObservation

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.26

Last changed2.70

Consumer names

Fibroblast growth factor 23 3rd specimen after challenge, Blood

Part names

Fibroblast growth factor 23 ^3rd specimen post XXX challengeACncPtPlasQnIAArbitrary ConcentrationPoint in time (spot)PlasmaImmunoassay

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.