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Test Code 1719 Magnesium, Urine, Timed

Performing Laboratory

Barnes-Jewish Hospital Laboratory


Colorimetric (Xylidyl Blue)

Literature Reference:

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

Specimen Requirements

Specimen Type: Urine, timed

Container/Tube: Brown urine container with green label (6N HCl)
Specimen Volume: Entire collection
Collection Instructions: Refrigerate specimen during collection.

Additional Information:

1. Starting and ending times of collection are required.

2. Follow instructions in Urine Collection in Special Instructions.

3. Plain, brown urine container is acceptable.

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

No established reference intervals

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

81050-Volume measurement for timed collection

Additional Information

For BJH Laboratory Use Only
Analyte Stability:

See Analyte Stability Chart in Special Instructions.

Specimen must be kept refrigerated during collection and before delivery to limit bacterial growth.

Laboratory Processing Instructions:

Test performed in BJH Core Lab. Mix urine well. Record volume, period, and pH on request form. Using 13x100 test tubes, prepare a 7-mL aliquot. If pH is >4, add 6 N HCl in 1 drop increments until the pH is between 2.5 and 4.0. Do not over adjust. Heat for 10 minutes at 56° C. Deliver to the automated line for centrifugation and delivery to Cobas 8000 for analysis. Completed specimen is stored refrigerated for 5 days.

Specimen Transport Temperature