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Test Code MG Magnesium

Specimen and Container/Tube

Specimen Type: Plasma

Preferred Specimen: Li-Heparin Mint Green Top

Other Acceptable specimens: Serum/Gold Top, Serum/Red Top

Specimen Stability

Storage Temperature

Stability

Room Temperature

7 days

Refrigerated

7 days

Frozen

1 year

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

  • Collect specimen per standard collection procedure and send to laboratory immediately. 

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Samples should be centrifuged within 2 hours of collection.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Aliquot sample into plastic transport tube containing a minimum of 0.2 mL of specimen.
  • Samples must be sent room temperature at 20-25oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours

Reference Values

Test

Age

Sex

Reference Range

Magnesium 

All

All

1.6 - 2.5 mg/dL

Critical Values

Analyte

Unit

Low

High

Age

Magnesium 

mg/dL

< 1.0

> 8.0

N/A

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: 1 hour

Routine Turnaround Time: up to 4 hours

Testing Schedule:  24/7

Clinical Indications

This assay is used for diagnosing and monitoring hypomagnesemia (magnesium deficiency) and hypermagnesemia (magnesium excess).

Test Components

Magnesium

CPT Codes

83735

LOINC Codes

19123-9

Methodology

Colormetric endpoint method (Roche Diagnostics)

Synonyms/Keyword Search

N/A

Additional Information

  • Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.

Last Review Date

3/19/25

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL