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Test Code 1522 Magnesium, Plasma

Performing Laboratory

Barnes-Jewish Hospital Laboratory


Colorimetric (Xylidyl Blue)

Literature References:

Package insert: Magnesium MG2 reagent. Roche Corporation, 03/2015.

Specimen Requirements

Specimen Type: Plasma
Container/Tube: Mint-green top (lithium heparin)
Specimen Volume: Full tube


Day(s) Test Set Up

Monday through Sunday
Turnaround Time:
STAT: 1 hour after receipt in laboratory
Routine: 2 to 4 hours after receipt in laboratory

Reference Values

1.4-2.5 mg/dL
Critical result (automatic call-back):
Non-labor and delivery patients: ≤0.4 mg/dL or ≥4.8 mg/dL
Labor and delivery patients: ≤0.4 mg/dL or ≥7.3 mg/dL

Literature Reference:

Tietz, Burtis CA, Ashwood ER, Bruns DE eds: Textbook of Clinical Chemistry and Molecular Diagnostics 5th ed: Chapter 52, p. 1733, Elsevier, St. Louis, MO 2012. 

Test Classification and CPT Coding


Additional Information

For BJH Laboratory Use Only
Alternate Tube:

1 dark green-top (lithium heparin) tube
1 red-top tube
Analyte Stability:

See Analyte Stability Chart in Special Instructions.

Laboratory Processing Instructions:
Test performed in BJH Core Lab.  Processed by automated line for delivery to the Cobas 8000. Completed specimens are stored refrigerated for 5 days. 

Specimen Transport Temperature


Special Instructions

LOINC Code Information

Name LOINC Code
Magnesium 19123-9