Mobile Site ›

Test Catalog

Test ID: MGCRU    
Magnesium/Creatinine Ratio, Random, Urine

Method Description Describes how the test is performed and provides a method-specific reference

Magnesium concentrations in urine can be determined by inductively coupled plasma-optical emission spectrometry. Aqueous acidic calibrating standards, quality control samples, patient specimens, and blanks are diluted with diluent containing an internal standard. In turn, all diluted blanks, calibrating standards, quality control samples, and patient specimens are aspirated into a pneumatic nebulizer and the resulting aerosol directed to the hot plasma discharge by a flow of argon. In the annular plasma the aerosol is vaporized, atomized, and then ionized. Emission signals from magnesium and the internal standard are observed radially by the emission spectrometer. Instrumentation response is defined by the linear relationship of analyte concentrations versus the ratio of the magnesium emission signals ratioed with the internal standard. After reagent blank subtraction, unknown sample magnesium concentrations are calculated by entering the net unknown intensity ratios into the linear calibration equation.(Nixon DE, Moyer TP, Johnson P, et al: Routine measurement of calcium, magnesium, copper, zinc, and iron in urine and serum by inductively coupled plasma emission spectroscopy. Clin Chem 1986;32:1660-1665)


Creatinine is measured using an enzymatic method based on the determination of sarcosine from creatinine with the aid of creatininase, creatinase, and sarcosine oxidase. The liberated hydrogen peroxide is measured via a modified Trinder reaction using a colorimetric indicator.(Package insert: Roche Diagnostics, Indianapolis IN, 2004)

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.

Monday through Friday; 11 a.m.

Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.

1 day

Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result

3 day

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

14 days

Performing Laboratory Location The location of the laboratory that performs the test