Magnesium (Serum)
Magnesium measured in blood serum — where only about 1% of your total body magnesium actually lives.
Included specifically so you understand its limitation: serum magnesium stays normal until deficiency is severe, because the body pulls from bone and muscle to defend it. It's the test most doctors order and the one least likely to find a problem.
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On its own, one marker is a data point. These panels include Magnesium (Serum) plus the markers that make it interpretable — each names every test, why it is on the list, and loads the whole set into your cart in one click at 10% off.
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Why your Magnesium (Serum) might be wrong
Most abnormal results are interference, not disease. These are the things that measurably move this specific marker — check them before you change anything. Each one says whether the number is wrong and should be repeated, badly timed and should be redrawn, or real with a cause worth explaining.
Under 1% of body magnesium is in the blood, and the body pulls it from bone and muscle to defend that fraction. A normal serum magnesium is entirely compatible with substantial whole-body depletion — which makes this one of the least useful tests routinely ordered.
Use RBC magnesium if the question is your status. Serum answers only acute questions.
Red cells rupturing in the tube spill their contents into the serum. Potassium, LDH, AST and magnesium are far higher inside cells than outside, so a haemolysed sample reports them falsely high. Caused by a difficult draw, a narrow needle, or shaking the tube.
The lab usually flags it. If your result is odd and the report mentions haemolysis, that is your answer — repeat the draw.
All deplete magnesium over time, and PPI-induced hypomagnesaemia can be severe enough to cause seizures.
Long-term PPI use warrants periodic magnesium checks.
What Magnesium (Serum) means in combination
A single marker tells you a little. Combinations tell you the story — these are the named patterns this marker takes part in, and what each one points at.
Under 1% of body magnesium is in the blood and the body pulls it from bone and muscle to defend that fraction. A normal serum magnesium is entirely compatible with substantial whole-body depletion — which makes it one of the least useful tests routinely ordered.
RBC magnesium answers the status question; serum answers only acute ones. PPIs, diuretics and alcohol all deplete it, and PPI-induced hypomagnesaemia can be severe.
What to test next
Markers rarely answer alone. These are the ones that put Magnesium (Serum) in context — each with its own full breakdown.
Frequently asked questions
1.6–2.3 mg/dL Ranges vary by laboratory and assay — always compare to the range printed on your own report.
Optimal ranges, root causes and the full correction protocol are available inside Coach Cam's Peptide Academy.
See the full breakdown inside the Academy.
See the full breakdown inside the Academy.
You can order Magnesium (Serum) directly through Marek Diagnostics without a doctor's visit — drawn at any Quest Diagnostics location in the US. Code CAMERON applies 10% off automatically.