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.

LOINCActiveBoth

LOINC Code 80958-2: Fractional excretion of magnesium (U+S/P) [Ratio]

Name: LOINC Code 80958-2: Fractional excretion of magnesium (U+S/P) [Ratio]
Creator: HealthAssure Clinical Team
Published: 2026-05-21T09:00:03.794Z

80958-2 is a LOINC code used to identify Fractional excretion of magnesium (U+S/P) [Ratio] 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 Fractional excretion of magnesium. It is commonly used with the system or sample type Urine+Ser/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 Fractional excretion of magnesium. It is commonly used with the system or sample type Urine+Ser/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: Both

What it does not mean

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

Key facts

Fractional excretion of magnesium [Ratio] in Urine and Serum or Plasma
Fractional excretion of magnesium
Chemistry; Fracti excret of Mg; MAG; Magnes; Mg; Pl; Plasma; Plsm; Point in time; QNT; Quan; Quant; Quantitative; Random; Ratios; Rto; SerP; SerPl; SerPlas; Serum; Serum or plasma; SR; UA; UR; Ur+SerPl; 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

Fractional excretion of magnesium (U+S/P) [Ratio]Fractional excretion of magnesium [Ratio] in Urine and Serum or PlasmaFracti excret of Mg Ur+SerPl-RtoFractional excretion of magnesiumCHEMFractional excretion of magnesium, Urine+BloodRatio

Frequently asked questions

Code details

Code80958-2

SystemLOINC

Display nameFractional excretion of magnesium (U+S/P) [Ratio]

DescriptionFractional excretion of magnesium

Short nameFracti excret of Mg Ur+SerPl-Rto

ComponentFractional excretion of magnesium

PropertyRatio

TimingPt

System (specimen)Urine+Ser/Plas

ScaleQn

ClassCHEM

Example units%

StatusACTIVE

Order/ObservationBoth

Flags

BillableNo

Valid clinical useNo

Source

SourceLOINC

Version2.82

Releasemain

First released2.56

Last changed2.56

Consumer names

Fractional excretion of magnesium, Urine+Blood

Part names

Fractional excretion of magnesiumRatioPtUrine+Ser/PlasQnPoint in time (spot)Urine and Serum or Plasma

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.