Ordering Recommendation

New York DOH Approval Status

This test is New York state approved.

Specimen Required

Patient Preparation

24-hour urine. Refrigerate during collection. Also acceptable: Random urine.

Specimen Preparation

Adjust pH to 1 by adding 6M HCl (approximately 10 mL HCl/24-hour specimen based on normal adult output of 1000-2000 mL/24 hours. Pediatric specimens will require less than 10 mL to reach the correct pH). Record total volume and collection time interval on transport tube and test request form.
Transfer 4 mL aliquot of urine from a well-mixed 24-hour collection to an ARUP Standard Transport Tube. (Min: 0.5 mL)

Storage/Transport Temperature


Unacceptable Conditions

Specimens containing preservatives other than HCl. Specimen submitted in metal containers.


Ambient: 3 days (if acidified); Refrigerated: 2 weeks; Frozen: 1 year


Quantitative Spectrophotometry




Within 24 hours

Reference Interval

Effective August 15, 2011

12-199 mg/d

Interpretive Data

Per 24h calculations are provided to aid interpretation for collections with a duration of 24 hours and an average daily urine volume.  For specimens with notable deviations in collection time or volume, ratios of analytes to a corresponding urine creatinine concentration may assist in result interpretation.

Compliance Category



Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
0020207 Creatinine, Urine - per volume 2161-8
0020208 Creatinine, Urine - per 24h 2162-6
0020211 Magnesium, Urine - per volume 19124-7
0020212 Magnesium, Urine per 24h 24447-5
0097110 Total Volume 19153-6
0097111 Hours Collected 30211-7
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • Magnesium/Creatinine, Random, Urine
  • Mg
Magnesium, Urine