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HelpTest Code LAB406 Magnesium - 24 Hour Urine
Department
CHEMISTRY
Collection Requirements
24 hour urine.
Do not add preservatives to the collection container.
Keep the container on ice or refrigerated during collection.
Primary Collection Container
24 HR Urine container
Transport
Urine refrigerated
Preferred Transport Temperature
Refrigerated
Processing
Measure total volume.
Adjust pH to less than 3 with 6N HCl.
Aliquot, centrifuge and refrigerate.
Note total volume and PH on the label.
Stability
Ambient: 1 week
Refrigerated: 1 week
Minimum Testing Volume
0.1 mL
Reference Range
74 – 124 mg/24hr
Methodology
The magnesium method is a modification of the methylthymol blue (MTB) complexometric procedure described by Connerty, Lau, and Briggs. MTB forms a blue complex with magnesium. Calcium interference is minimized by forming a complex between calcium and Ba-EGTA (chelating agent). The amount of MG-MTB complex formed is proportional to the magnesium concentration and is measured using a bichromatic (600 and 510 nm) endpoint technique. Siemens Dimension Vista.
Performed
Sunday – Saturday
Reported
As completed
CPT Codes
83735
Unacceptable Conditions
Urine not acidified.
Additional Information
Other acceptable preservative is KBS.
pH must be <4.0.