Urine Magnesium/Creatinine Ratio
Measures the relative amount of magnesium compared with creatinine in a urine sample, which can help evaluate magnesium levels and kidney function.
["This urine test helps determine whether the body is excreting an appropriate amount of magnesium."]
Key facts at a glance
- LOINC
- 13474-2
- Short code
- Magnesium/Creat Ur
- Synonyms
- Magnesium/Creat 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 magnesium and creatinine in urine and compares their amounts as a ratio. Creatinine is a waste product that reflects urine concentration, so the ratio can help show how much magnesium is being lost in the urine.
Why might I need this test?
Your clinician may order this test to evaluate magnesium balance, investigate unusual magnesium levels in the blood, or assess how well your kidneys are handling magnesium. It may also be used when monitoring certain medicines or conditions that affect electrolyte levels.
How is the test performed?
A urine sample is collected in a laboratory-provided container and tested to determine the amounts of magnesium and creatinine. The laboratory then calculates the magnesium-to-creatinine ratio. Follow the specific collection instructions given by your healthcare provider.
How do I prepare for the test?
Preparation depends on whether a single urine sample or a timed collection is required. A 24-hour collection involves saving all urine for the full period, while a spot sample is collected at one time. Your clinician or laboratory will explain the correct timing, container, and any medicine-related instructions.
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.
A higher-than-expected ratio may indicate that more magnesium than expected is being lost in the urine, which can occur with some kidney disorders or medicines. A lower ratio may reflect reduced intake, dilution of the urine sample, or other conditions affecting magnesium balance. Results should be interpreted with your symptoms, medications, kidney function tests, and the type of urine collection performed.
Short name
Urine magnesium/creatinine ratio
Frequently asked questions
Is this the same as a serum magnesium test?
Why is creatinine included in the result?
Do I need to stop taking my medicines before this test?
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