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Test Code LAB406 Magnesium, 24 Hour Urine

Clinical System Name

Urine Magnesium Quantitation, 24 Hours



Sample Requirements

Specimen: Urine

Container(s): 24 Hour Urine Jug

Preferred Vol: Entire volume from 24 hr collection.

Minimum Vol: N/A


Note:   Please contact lab to obtain urine container (no preservatives are needed) - go to Cinical Lab with patient label to obtain urine container.  Refrigerate sample during collection period.  Document start and stop dates/times, along with patient information.  Deliver labeled container to Clinical Lab upon completion.


Processing Instructions

Reject due to:

Spin: N


Temp: 2-8 C

Storage location: Store original container in CPA refrigerator, with remaining labels in CPA refrigerator, FrigB bucket.


Off-site collection: No preservatives are needed to start collection. Document start and stop dates and times, along with patient information. Send entire original container refrigerated.


Specimen Type Temperature Time
  Room temp 7 d
  Refrigerated 7 d
  Frozen 1 m



STAT Performed TAT
N M - F 1 - 3 d


Performing Laboratory

Seattle Children's Laboratory    


Department:  Chemistry

Location: Chem East

Phone Number: (206) 987-2617

CPT Codes



Method: Spectrophotometry by Vitros 4600

Analytical Volume: 0.5 mL

Limitations: Method is affected by fecal contamination, loss of specimen during collection, Loss of 10% of total urine collected invalidates the test.

Reference Range

4 - 122 mg/ 24 h


Magnesium excretion exhibits a diurnal variation and is directly dependent on dietary intake.