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Magnesium, 24 hour urine

Item Value
Approval req'd? Yes, if testing is requested between midnight and 8:00 AM.
Available Stat? No
Test code MGU
Test group Magnesium
Performed by Parnassus Chemistry
In House Availability Test available 7 days per week from 8:00 AM to midnight only.
Method Spectrophotometric (calmagite dye)
Collection Instructions Keep container refrigerated during collection. Indicate hours of collection on requisition.
Container type 24 hour urine collection container

Click here for Urine Preservative Requirements
Amount to Collect Entire 24 hour urine output.
Sample type 24 hour urine collection
Preferred volume 2 mL urine
Min. Volume 1 mL urine
UCSF Rejection Criteria Container not refrigerated during collection.
Processing notes Aliquot 2 mL and add 1 drop of 6N HCl to acidify.
Units mg/D
Normal range 73-122 mg/D

See Additional information.
Synonyms Mg
Stability Refrigerated 2 days
Turn around times Test run 2x daily. Results available at 1400 & 2000
Additional information Output varies with the diet.

To convert mg/d to mmol/d (SI units) multiply by x 0.411.

Gadolinium MR contrast agents including Gadodiamide (Omniscan), Gadoversetamide (Optimark), Gadopentetate Dimeglumine (Magnevist), and Gadoterdiol (Prohance), have been shown to interfere with certain colorimetric assays used in the measurement of various serum cations including iron, magnesium, and calcium. The UCSF clinical labs utilize a colorimetric assay for the measurement of both serum iron and serum magnesium that are subject to this interference. For serum magnesium, some gadolinium containing agents (Gadodiamide and Gadoversetamide) may produce a falsely elevated result (on average 117 and 124% respectively, of the true serum magnesium concentration). See "Calcium" and "Iron" entries for respective interferences.

Reference:Proctor et al. Gadolinium Magnetic Resonance contrast Agents produce Analytic Interference in Multiple Serum Assays. Am J Clin Pathol. 2004;121:282-292.
Last Updated 3/24/2013 7:46:08 PM
Entry Number 638
Lab Procedure Link Click here for Procedure
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