Magnesium (serum) Blood Test
£49.00
A Magnesium Blood Test measures the level of magnesium in your bloodstream. Magnesium is a vital mineral that plays a crucial role in numerous bodily functions, including supporting bone health. While the majority of magnesium is stored in the bones, it also helps regulate muscle function, nerve activity, and energy production, contributing to overall well-being.
What does it test for?
- Magnesium – Serum
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Biomarkers
Magnesium (Mg)
Information
Have you been feeling any of these symptoms lately?
The Magnesium (Serum) blood test is recommended for individuals who may be experiencing one or more of the following symptoms, as low magnesium levels can impact various bodily functions:
Nausea: Persistent or unexplained nausea can be a sign of magnesium deficiency.
Weakness: General fatigue or muscle weakness may indicate an imbalance in magnesium levels, which is crucial for muscle function.
Muscle Twitches and Cramps: Involuntary muscle twitches, spasms, or cramps can result from low magnesium, as it plays a key role in muscle relaxation.
Neurological Issues: Conditions like epilepsy or depression can be linked to magnesium deficiencies, as magnesium is involved in brain function and mood regulation.
Weak Bones: Magnesium is essential for bone health, and a deficiency may contribute to weakened bones or increased risk of osteoporosis.
Rapid Heartbeat: Magnesium helps regulate the heart’s electrical activity. A deficiency can cause arrhythmias or an unusually fast heart rate.
Abnormally High Blood Pressure: Low magnesium levels have been associated with elevated blood pressure, which could contribute to hypertension.
Additional Insight from Dr Sameer Nakedar, MBBS, MRCGP, PGCert
Magnesium Imbalance: Causes and Symptoms
Magnesium is an essential mineral that plays a crucial role in many bodily functions, including muscle and nerve function, heart rhythm regulation, and bone health. Both low and high levels of magnesium can lead to various health issues.
Low Magnesium Levels: Low magnesium levels can result from several factors, including excessive loss of magnesium through the gut or kidneys, or certain medications. Common causes include gastrointestinal issues, kidney disease, or the use of diuretics, antibiotics, or other medications that interfere with magnesium absorption.
Symptoms of Low Magnesium: Low magnesium levels can cause a range of symptoms, such as:
Muscle weakness and cramps
Pins and needles sensation (paresthesia)
Irregular heartbeats (arrhythmias)
Raised blood pressure
General weakness and fatigue
Seizures
Drowsiness or confusion
Sources of Magnesium
Magnesium is found in various foods, especially those rich in fiber. Key dietary sources include:
Green leafy vegetables (e.g., spinach, kale)
Bananas
Wholemeal bread and brown rice
Avocados
Certain fish and meat
High Magnesium Levels
High magnesium levels are less common but can occur due to excessive supplementation or the overuse of medications such as antacids, which contain magnesium. This condition is known as hypermagnesemia.
Symptoms of High Magnesium
Excess magnesium in the body can lead to symptoms including:
Stomach upset and diarrhea
Breathing difficulties
Eye irritation
Heart arrhythmias
Weakness
Nausea and vomiting
It’s important to monitor magnesium intake, particularly if taking supplements or medications that affect magnesium levels. Maintaining a balanced magnesium level is key to overall health.
Additional Information
Symptoms of Low Magnesium Levels
Low magnesium levels can lead to a variety of symptoms, including:
Weakness: Feeling unusually fatigued or lacking energy.
Nausea: A feeling of sickness or queasiness.
Vomiting: Throwing up, which can further deplete magnesium levels.
Muscle Cramps: Painful, involuntary muscle contractions.
Heart Rhythm Problems: Irregularities in the heart rate, which may be serious and require medical attention.
If you experience any of these symptoms, it’s important to consult with a healthcare provider.
Magnesium Blood Test: If your doctor suspects you have low magnesium levels, they may order a blood test. This test can measure your magnesium levels and help determine whether treatment is necessary. Early detection and correction of magnesium deficiency are essential for preventing complications, especially those related to muscle and heart function.
Why take the test?
The Magnesium (Serum) Blood Test is used to assess magnesium levels in your blood and identify potential deficiencies, a condition known as Hypomagnesemia. The test measures the concentration of magnesium (Mg) and helps determine if you require treatment. Along with your test results, you will receive expert comments from our certified doctors to help interpret the findings.
Both low and high levels of magnesium in the blood can lead to significant health problems. Magnesium deficiency is often associated with symptoms such as:
-Weakness
-Irritability
-Cardiac arrhythmias (irregular heartbeats)
-Vomiting
Magnesium deficiency has also been linked to neurological issues, including depression and migraines. The body normally regulates magnesium levels to maintain a balance, eliminating excess magnesium while preventing deficiency. However, certain individuals are at a higher risk of magnesium deficiency, such as those with type 2 diabetes or alcohol use disorder, who may experience reduced magnesium levels in their blood.
If you or someone you know is experiencing any of the above symptoms, it may be an indication of low magnesium levels. A blood test can help confirm this and guide appropriate treatment to restore balance.
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The Magnesium Blood Test helps assess whether your magnesium levels are within the normal range. It can detect if your levels are too high (a condition known as hypermagnesemia) or too low (referred to as hypomagnesemia). Regular monitoring can help ensure your magnesium levels are balanced, promoting overall health and well-being.

Dr Sameer Nakedar
MBBS, MRCGP, PGCert
Collecting a blood sample for your finger prick home test is simple and easy to do. Watch the video below for step-by-step instructions on how to perform the test at home.
1. Pick your home test
We offer a comprehensive range of tests to meet your health needs. With next-day delivery across the United Kingdom, you can avoid the hassle of sitting in a doctor’s office or clinic. Take our quiz to easily find the perfect test for you.
2. Take your test
Activate your test and collect your sample in the morning. Simply return your sample the same day using the prepaid shipping label provided. The sample is collected using a quick and easy finger prick method, which takes only about 5 minutes to complete.
3. Results within 48 hours
You’ll receive verified results along with clear insights into what your biomarkers mean. Order now and take the first step toward becoming a healthier version of yourself!
Magnesium (serum) Blood Test Information
Specification of Magnesium (serum) Blood Test
Also Known As / Related Tests: Magnesium Deficiency Test, Hypomagnesemia Test
Biomarkers Tested: Magnesium (Mg) levels
Test Tube: Standard serum collection tube
Brand: Welzo
Turnaround Time: Approximately 24 hours
Lab Test Ranges:
Test Kit Certification: MHRA/UKCA approved
Lab Location: United Kingdom
What does a Magnesium (serum) Blood Test for?
Are Magnesium (serum) Blood Tests available on the NHS?
Frequently Asked Questions
What causes high magnesium levels?
High magnesium levels, also known as hypermagnesemia, can result from several factors, including:
Kidney Failure: When the kidneys are unable to properly filter and eliminate magnesium, it can accumulate in the bloodstream.
Certain Medications: Some medications, such as antacids, laxatives, or diuretics, can contribute to elevated magnesium levels.
Dietary Supplements: Overuse of magnesium supplements, especially without medical supervision, can lead to excessive magnesium levels in the body.
What is a normal magnesium serum level?
Where do I send my sample?
You will receive a free return label to send your health test samples back to our lab for analysis. Clear instructions, including return details, will be provided via email to ensure a smooth and hassle-free process.
What do I need to do before my test? i.e. fast, no drinking, etc
If fasting or limiting alcohol intake is required before your blood test, we will send you personalized instructions via email after your order is placed. However, most tests can be taken without the need for fasting.
When will I get my results/how will I receive my results?
Results are typically processed within 2–3 working days. If a sample is sent over the weekend (which we do not recommend), you will receive your results within 2–3 days from the following Monday. Once your results and personalized report are ready, you will receive an email notification with instructions to log in to the Welzo online platform and view your results.
What is a magnesium serum blood test?
In addition to diagnosing magnesium deficiency, the test is also useful for monitoring magnesium levels in individuals who are taking magnesium supplements or medications that may affect magnesium balance. Regular monitoring ensures that magnesium levels stay within a healthy range, preventing potential complications related to both deficiency and excess.
What happens if serum magnesium is low?
If your serum magnesium levels are low, you may experience a range of symptoms, including:
Muscle weakness
Muscle cramps
Seizures
Anxiety
In addition, low magnesium can lead to low calcium levels, which may contribute to conditions like osteoporosis. If magnesium deficiency is left untreated, it can result in severe complications and, in extreme cases, may be life-threatening. Prompt treatment is essential to restore healthy magnesium levels and prevent further health issues.
What if my results show that I’m outside the normal range?
If your results fall outside the normal range and raise concerns, it is crucial that you contact your GP or emergency services immediately by calling 111 or 999. Please remember: if you feel unwell or are concerned about your health, do not wait for test results—reach out to emergency services as soon as possible.
Disclaimer: If your test results are abnormal, we are not responsible for follow-up treatments or for notifying a healthcare professional. By taking a test with us, you agree to take the necessary steps to follow up with a healthcare provider independently.
Where does my information go, and is the system secure?
Once you register with our platform, your details are securely encrypted and pseudonymized. Your sample will be sent to our lab and registered using an encrypted HL7 file (Health Level Seven International), a standard for exchanging and managing electronic health records (EHRs). To further protect your privacy, your data and sample will be pseudonymized, meaning an unidentifiable alphanumeric code will be applied to your account. This enhances the security and anonymity of your information.
