The magnesium test is a direct blood measurement of total serum magnesium, which holds less than 1% of the body's magnesium. Practitioners use it to identify clear deficiency, monitor clients on PPIs or diuretics, and put cramps, palpitations or poor glucose control in context. A result inside the range does not rule out low body stores, and haemolysis or low albumin can distort it.
| Test type | Measured in a blood sample |
|---|---|
| Measurements required | Magnesium only |
| Sample and collection | Blood draw at a collection centre |
| Preparation | This test doesn't need fasting on its own. |
| Turnaround | 3 to 5 business days |
| Available through | Calcium, Phosphate & Magnesium, part of the Baseline Health Check. Also in: Full Body Health Check. |
| Pricing | Included in the $99 Baseline Health Check |
| Results | Returned in the Vively practitioner platform, beside your client's other markers |
What are the Magnesium reference and optimal ranges?
| Typical lab reference | Vively optimal | |
|---|---|---|
| Adults | 0.70 to 1.10 mmol/L | No separate optimal range |
Labs differ, so read the result against the range printed on the client's report (RCPA guidance). A result inside the range does not rule out low body stores.
Check a client's Magnesium result
Enter the value from your client's lab report to see where it sits against the typical lab range and the Vively optimal range.
A guide only, not a diagnosis. One result is a starting point: read it with symptoms, history and a repeat test. Labs differ, so check the result against the range on your client's report. Nothing you enter is stored or sent.
How do you arrange Magnesium testing through Vively?
- Get verified. Practitioners with a recognised qualification or membership (ATMS, NHAA, ANTA, Dietitians Australia, NSA, CMA or Ahpra registration) can request free practitioner access.
- Choose a panel. Log in to the practitioner platform and pick a panel that includes Magnesium, or build your own. It is included in the $99 Baseline Health Check.
- Client collects. Your client collects at a partner collection centre, with their request on their phone or printed.
- Review results. Results come back to you in the practitioner platform, beside your client's other markers, ready for the follow-up consult.
Which Vively panels include Magnesium?
Log in to the practitioner platform to view a panel in full, or build and save your own from 100+ tests and panels.
- Baseline Health Check74 markers across 11 lab groups$99
One fasting blood draw.
Full Blood CountUrea, Electrolytes & CreatinineLiver Function TestsCalcium, Phosphate & MagnesiumLipid StudiesDiabetes & Glycaemic StudiesIron StudiesThyroid Function Tests+3 moreLog in to view this panel - Log in to view this panelFull Body Health Check87 markers · Health checksPrice on sign-up
How do you read Magnesium without an optimal range?
Magnesium has no separate optimal range: serum stays in range while tissue stores fall, so treat 0.70 to 0.85 mmol/L as a prompt to look closer.
The kidneys and bone hold serum magnesium steady, so it often stays in range while tissue stores fall, and a low serum value usually means depletion is well established.
Costello and colleagues (Advances in Nutrition, 2016) proposed 0.85 mmol/L as a more realistic floor. A result of 0.70 to 0.85 mmol/L prompts a closer look at diet, losses and symptoms, without labelling it deficient.
Add medications and the trend. Use potassium and calcium where available.
What should Magnesium be read with?
- LowLow-normal magnesium with high HOMA-IR or fasting insulin
Often seen with insulin resistance, where urinary magnesium losses rise.
- LowLow magnesium in a client on a PPI or diuretic
Long-term PPIs reduce gut absorption and loop or thiazide diuretics raise urinary loss; the GP should review the medication.
- LowLow magnesium with raised GGT
Possible regular heavy alcohol intake, which increases urinary magnesium loss.
- HighHigh magnesium with low eGFR
Points to reduced kidney excretion, often with magnesium supplements, antacids or laxatives; needs GP review.
- LowLow magnesium with low vitamin D
Magnesium is needed to activate vitamin D, so correcting magnesium can help the vitamin D response.
What can affect a Magnesium result?
- Haemolysis or delayed separation raises the result, as red cells hold several times the serum concentration
- Low albumin lowers total magnesium, as about 30% is protein-bound
- Magnesium supplements, antacids and laxatives taken shortly before collection can raise it
- Long-term PPIs, loop and thiazide diuretics, and alcohol lower it
- Diarrhoea, poorly controlled diabetes and heavy sweating increase losses
- Reduced kidney function raises it
When should you refer the client to their GP?
- Below 0.5 mmol/L, or any low result with palpitations, tremor, muscle spasms or seizures
- Above the lab range, particularly with reduced eGFR or regular use of magnesium-containing laxatives or antacids
- Low magnesium in a client on a PPI or diuretic: the medication decision sits with the GP
- Low magnesium alongside low potassium or calcium on the same report
How should a client prepare for a Magnesium test?
Copy or print this to send to your client.
Preparing for your Magnesium test
- This test doesn't need fasting on its own.
- If your practitioner has requested the Baseline Health Check, fast for 8 to 12 hours before a morning collection (water is fine).
- Tell your practitioner if you take magnesium supplements, reflux medicines called PPIs (such as omeprazole) or diuretics (fluid tablets).
- Take your pathology request to any of 4,000+ collection centres. Bring it printed or on your phone.
- Keep taking prescribed medicines as usual unless your doctor tells you otherwise.
- Results usually take 3 to 5 business days and come to your practitioner. Book your results appointment for after that.
How do practitioners use Magnesium with clients?
Start with intake: leafy greens, legumes, nuts, seeds and wholegrains cover most clients' needs, and a diet history often explains a low-normal result faster than more testing. Chronic stress, alcohol and some medications can increase losses, so ask about all three before suggesting a supplement, and involve the GP when a medication is the likely cause.
Magnesium FAQs
Can a naturopath, nutritionist or dietitian order a magnesium test through Vively?
Yes. Add it to a client panel on the Vively practitioner platform. It is part of Calcium, Phosphate & Magnesium in the $99 Baseline Health Check, and is also in Full Body Health Check. No account yet? Request free access.
Is red cell magnesium better than serum magnesium?
It may reflect tissue stores more closely, but it is less standardised and the evidence is mixed. Vively's Baseline measures serum magnesium. For most clients, serum magnesium read with diet history, symptoms, medications, potassium and calcium is a reasonable start. If depletion is suspected despite a normal serum result, discuss further testing with the client's GP.
Should clients stop magnesium supplements before testing?
No standard washout exists. A dose in the hours before collection can lift serum magnesium slightly, so ask the client to take that day's dose after the blood draw. Record the product and usual intake so repeat results are comparable, and keep any prescribed magnesium unchanged unless the GP advises otherwise.
Can serum magnesium be normal when body stores are low?
Yes. Serum holds less than 1% of the body's magnesium, and the kidneys and bone keep it steady, so a low serum value usually means depletion is well established. Some researchers argue the lower limit is too low and propose 0.85 mmol/L. A result between 0.70 and 0.85 mmol/L is a reason to look at diet, losses and symptoms, not a diagnosis.
What can make a serum magnesium result read falsely high or low?
Haemolysis or delayed separation raises it, because red cells hold several times the serum concentration. Low albumin lowers total magnesium, as about 30% is protein-bound. Magnesium supplements, antacids and laxatives taken shortly before collection can raise it. Ask about all three, and request a prompt, clean collection when you repeat a surprising result.
References
- Royal College of Pathologists of Australasia. RCPA Manual: Magnesium.
- Pathology Tests Explained. Magnesium.
- Costello RB, Elin RJ, Rosanoff A, et al. Perspective: the case for an evidence-based reference interval for serum magnesium: the time has come. Advances in Nutrition. 2016. Source