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Test Code LAB406 Magnesium, Urine, 24 Hour

Performing Laboratory

Barnes-Jewish Hospital Laboratory

Methodology

Colorimetric (Xylidyl Blue)

Literature Reference:

Package insert: Magnesium MG2 reagent. Roche Corporation, 03/2022.

Specimen Requirements

Specimen Type: Urine, 24 hour

Container/Tube: Plain, brown urine container or 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. See Urine Collection information under General Information.

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

Test Classification and CPT Coding

81050-Volume measurement for timed collection

83735-Magnesium

Reference Values

0-18 years: No established reference range

>18 years and up: 70-150 mg/24 hours

Literature Reference:

1.  Rifai N, Horvath AR, Wittwer AT eds: Textbook of Clinical Chemistry and Molecular Diagnostics 6 th ed: Chapter 64, p. 1422, Elsevier, St. Louis, MO 2018.

2.  Rifai N, Horvath AR, Wittwer AT eds: Textbook of Clinical Chemistry and Molecular Diagnostics 6 th ed: Chapter 69, p. 1655, Elsevier, St. Louis, MO 2018.

Specimen Transport Temperature

Ambient

Additional Information

For BJH Laboratory Use Only
Analyte Stability:

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.

Special Instructions

See Urine Collection information under General Information.

See Analyte Stability Chart under General Information for a complete list.
 

LOINC Code Information

Name LOINC Code
Magnesium in 24 hour urine 32024-2
Collection duration 13362-9
Volume of urine 19153-6