Magnesium Levels Blood Test
Below is a plain-language overview of the magnesium levels blood test. A magnesium levels blood test measures the amount of magnesium in your blood. Magnesium is a mineral that helps muscles, nerves, and the heart work properly. This test is ordered when a doctor suspects your magnesium level is too high or too low, often due to kidney problems, digestive issues, or certain medications.
- Sample type
- blood
- Category
- Vitamin & Mineral
- Turnaround
- 1-3 business days
- Price
- $28
- Referral
- Not required
A magnesium levels blood test measures the amount of magnesium in your blood. Magnesium is a mineral that helps muscles, nerves, and the heart work properly. This test is ordered when a doctor suspects your magnesium level is too high or too low, often due to kidney problems, digestive issues, or certain medications.
What it measures
- Total Magnesium — The main measurement of magnesium in your blood.
- Ionized Magnesium — The active form of magnesium, sometimes measured separately.
- Albumin — A protein that binds magnesium; may be checked to interpret total magnesium.
Who it is for
Doctors typically order this test for people with symptoms of magnesium imbalance, such as muscle cramps, weakness, irregular heartbeat, or fatigue. It may also be ordered if you have kidney disease, take certain diuretics, or have long-term digestive problems.
Preparation
Usually no special preparation is needed. You can eat and drink normally unless your doctor tells you otherwise. Some medications can affect magnesium levels, so tell your doctor about all medicines you take.
Results and what they mean
Results are reported as a number in milligrams per deciliter (mg/dL). Your doctor will interpret the result based on your health history and other tests. A low or high result does not always mean a problem, and only a clinician can determine what it means for you. This is general information, not medical advice.
How to order this test
- Choose the test and place a confidential order online.
- Select a certified collection site and pick a time that suits you.
- Have your specimen collected — most draws take only a few minutes.
- Review results in a secure portal, typically within 1–3 days.
Preparation, hours, and pricing vary by site; confirm details directly with the lab before your visit.
Availability by state
Direct-access online ordering for the magnesium levels blood test is available in most states. It is currently unavailable in 6 states:
Everywhere else you can order confidentially and collect your sample at a certified site. Browse by state →
Frequently asked questions
Do I need to fast for a magnesium blood test?
No, fasting is usually not required. You can eat and drink as normal unless your doctor gives different instructions.
What can affect my magnesium test results?
Medications such as diuretics, antacids, and some antibiotics can affect levels. Also, having a high or low level of other minerals like calcium can influence results.
How soon will I get my results?
Results are typically available within 1 to 3 business days. Your doctor's office will contact you about the results.
Is this test covered by insurance?
Most insurance plans cover medically necessary blood tests. Check with your insurance provider for specific coverage details.