Sign in →

Test Code LAB405 Magnesium, Urine, Random

Performing Laboratory

St. Louis Children's Hospital Laboratory - Chemistry

Specimen Requirements

Patient Preparation: None

Collection Container/Tube:

Preferred: Clean, plastic screw-cap urine collection container with no preservatives

Acceptable: Any clean, plastic collection container, no preservatives

Specimen Collection Volume: 5.0 (minimum 0.5 mL) urine

Submission Container/Tube: If specimen is coming from outside facility aliquot a minimum of 0.5 mL of urine into a plastic screw-capped tube for transport.

Special Instructions: Send to lab promptly.

 

Sample Rejection

Mislabled or unlabeled specimens

Logistics

Test Availability: Monday-Sunday

Cut-off time: None, performed as received

Turnaround Time: Same Day; 2 hours from receipt in performing lab

Reference Values

Reference Interval: No reference intervals established

Critical Value: None established

 

Methodology

Colorimetric Endpoint

Limitations

  • NA

Additional Information

FOR SLCH CORE LABORATORY USE ONLY

Lab Processing Instructions: Mix well and aliqout minimum of 0.5 urine into a Roche-false bottom tube. If specimen is turbid or precipitates are present, mix well and aliquot into plastic container to centrifuge to clear then aliquot cleared urine into the Roche-false bottom tube for testing. 

Processed Volume: minimum 0.3 mL urine

Analyte Stability:

Specimen Type Temperature Time
urine (non-acidified)    Ambient or Refrigerated    4 hours non-acidified   
urine (acidified)        Ambient 2 days    
  Refrigerated     3 days     
  Frozen  1 year      
If specimen is >4 hours old, acidify with hydrochlorid acid to pH <1

 

Test Classification and CPT Code

83735

LOINC

19124-7

Last Reviewed

07/2025