Magnesium and Creatinine, 24-Hour Urine
Measures magnesium and creatinine in all urine collected over 24 hours to assess magnesium excretion and help evaluate whether the collection was complete.
["This test measures how much magnesium your body releases in urine over one day."]
Key facts at a glance
- LOINC
- 44336-6
- Short code
- Magnesium/Creat 24h Ur
- Synonyms
- Magnesium/Creat 24h Ur
- Category
- kidney
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 1.7
- Ref high
- 2.2
- Critical range
- 1 N/A – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 83735
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This test measures the amount of magnesium and creatinine in urine collected for 24 hours. Magnesium is a mineral needed for normal muscle, nerve, heart, and bone function, while creatinine is a waste product used to help check the completeness of urine collection.
Why might I need this test?
A clinician may order this test to evaluate magnesium balance, investigate unusual magnesium levels in the blood, or assess kidney function and medication effects. Measuring creatinine along with magnesium can help determine whether all urine was collected and whether magnesium excretion is unusually high or low.
How is the test performed?
You collect all urine into a labeled container for exactly 24 hours, following the instructions provided by the laboratory. The container is then submitted for laboratory analysis.
How do I prepare for the test?
Follow the laboratory's collection instructions and record when the collection starts and ends. Tell your clinician about medicines, supplements, and recent illness, because these can affect magnesium levels. Do not change prescribed medicines unless your clinician instructs you to do so.
Reference range
Adult: 1.7-2.2 mg/dLN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low urinary magnesium may reflect poor intake, reduced intestinal absorption, or increased loss through the kidneys. High urinary magnesium may occur with excess supplementation, certain kidney conditions, or medications that increase magnesium excretion. Results should be interpreted with the blood magnesium level, kidney function, medicines, and collection quality.
Short name
24-Hour Urine Magnesium
Frequently asked questions
Why is creatinine measured with 24-hour urine magnesium?
How do I collect a 24-hour urine sample?
Does an abnormal result always mean I have a magnesium disorder?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy