24-hour urine magnesium test
Quick answer: This test measures how much magnesium your kidneys pass into urine over 24 hours. Doctors use it to find the cause of low or high blood magnesium and as part of a kidney stone work-up.
- Sample24-hour urine
- Takes24 hours of collection at home
- Before the testCollect all your urine for 24 hours in the container provided, following the lab's instructions.
How the test is done
- 1The lab gives you a collection container and instructions
- 2You start after flushing the first morning urine, noting the time
- 3You collect every urine sample over the next 24 hours
- 4You finish with the next morning's first urine and return the container promptly
What your results can mean
Reading your report
Normal ranges differ between labs and by age and sex, so discuss your result with your doctor.
If the result is outside the usual range
A high level can be seen when the kidneys are losing magnesium, for example with some water tablets or kidney conditions. A low level can be seen when the body is short of magnesium, such as with poor intake or bowel problems.
Who usually has this test
People with unexplained low or high blood magnesium, or with repeated kidney stones.
Risks and aftercare
Collecting urine carries no physical risk; drink your usual amount so the sample reflects a normal day.
Names and options
Also called: urine magnesium
Listed by the hospital as
- 24 HR URINE MAGNESIUM
Questions about this test
Why would my doctor check magnesium in urine instead of blood?
A urine test shows how much magnesium the kidneys let go. If blood magnesium is low, this helps tell whether it is being lost through the kidneys or not absorbed from food.
Do supplements affect a 24-hour urine magnesium test?
Yes, magnesium supplements and some antacids or laxatives can raise the amount in urine. Tell your doctor what you take, but do not stop anything without their advice.
What role does magnesium play in kidney stones?
Magnesium in urine can help stop calcium oxalate stones from forming. A low urine magnesium may be one of several factors your doctor looks at in a stone work-up.
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Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
Get directions ↗IVF Pulse fertility care at Tamara Hospital →
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.