Magnesium, whole blood and red blood cell

B -Mg ATK 8006

E -Mg KL 2300

Magnesium holds a pivotal role as a crucial trace element within the body, functioning as a co-factor for no less than 300 enzymes, actively participating in various metabolic processes. In adults, roughly 54% of magnesium resides in bones, while 45% is distributed throughout muscles and other soft tissues. Magnesium plays a fundamental role in the production of ATP, a molecule of great importance in cellular energy metabolism, muscle contractions, and nerve impulse transmission. Additionally, magnesium contributes to the structural stability of RNA and DNA and plays a role in various stages of protein synthesis. The heart muscle’s contractility, impulse initiation, and conduction are also influenced by magnesium.

Approximately 1% of magnesium exists outside cells, with around 70% of the magnesium in the bloodstream being intracellular. The primary absorption of magnesium occurs within the small intestine, with a smaller portion being absorbed in the large intestine. Factors such as the presence of phytate in vegetables and a low protein intake can diminish magnesium absorption. Kidneys are chiefly responsible for regulating magnesium balance.

The magnesium concentration in whole blood or red blood cells provides an accurate reflection of the body’s magnesium status.


Investigating magnesium levels in the body. Suspected magnesium deficiency in fluid therapy, parenteral nutrition, malabsorption, renal insufficiency, diuretic therapy. Cardiac arrhythmias, tachycardia, changes in ECG (prolonged QT interval). Increased neuromuscular excitability (tetany, muscle twitches).


B -Mg 5 mL of lithium-heparin blood
E -Mg 10 mL of lithium-heparin blood (3 mL of red blood cell mass, see instructions below)

Mix the sample well. The tube must not contain any clots. Take trace element samples last in order to cleanse the sampling needle of possible trace element residues. If this is the only test requisition, first take one extra tube.

No fasting is needed. No trace element supplements 12 hours before sampling. The result is normalised to whole blood hematocrit (Hct) value (B -PVK, engl. Complete Blood Count, B -CBC). The client should determine the hematocrit prior to shipping the sample and write the result on the test requisition.

The Hct is essential for interpretation of results. Without a measured Hct value, standard Hct is used.

E -Mg sample treatment

➢ centrifuge the whole blood tube
➢ after centrifugation, remove the plasma and white blood cells off the top of the red blood cells
➢ add a 0.9% NaCl solution volume equivalent to the plasma into the tube
➢ mix the sample by turning
➢ centrifuge
➢ remove the wash solution (NaCl) off the top of the red blood cells
➢ mix well before shipping

Storage and delivery

Ship at room temperature on sampling day (shipping Mon-Thu). Store frozen over the weekend, ship at room temperature.


ICP-MS, Accredited method (B -Mg)

Turnaround time

10 weekdays

Reference ranges, calculated

B -Mg:

women 1.14 – 1.62 mmol/L (Hct 0.39)
​men 1.19 – 1.71 mmol/L (Hct 0.42)

The Hct value affects the reference ranges. The same sample can be used to measure Cu, K, Mn, P, Se and Zn.

E -Mg   1,76 – 2,67 mmol/l

The reference areas have been calculated from the Mineral Laboratory Milan research database. Outliers that significantly differed from the reference distribution were excluded. A mid-percentile range of 90% has been established based on the refined dataset. The most recent update was in 2017.

Interpretation of results

Magnesium is readily accessible through various foods, with abundant amounts found in green vegetables, whole grains, nuts, and chocolate. Additional sources of magnesium include dairy products and mineral waters.

The symptoms associated with magnesium deficiency can be quite diverse due to magnesium’s integral role in numerous bodily functions. Deficiency-related symptoms can manifest within the central nervous system, muscles, gastrointestinal tract, and cardiovascular system. These symptoms often arise from conditions or medications that hinder magnesium absorption in the intestines or impede kidney function, leading to a deficiency. Neuromuscular symptoms encompass muscle twitches, muscle weakness, numbness, tingling, and leg cramps. Gastrointestinal symptoms encompass loss of appetite, nausea, abdominal pain, diarrhea, or constipation. Cardiovascular symptoms might involve ventricular arrhythmias. Additionally, magnesium deficiency can be linked to hypokalemia and hypocalcemia.

Beyond magnesium deficiency, severe kidney failure can potentially result in hypermagnesemia, especially in scenarios where magnesium-containing medications like antacids and laxatives are utilized. In such cases, symptoms mirror those of deficiency, including nausea and vomiting. Additional signs may encompass a decrease in blood pressure and the loss of deep tendon reflexes.

When it comes to monitoring changes in magnesium balance, serum or plasma measurements might not be suitable due to the efficient regulatory role of the kidneys in maintaining magnesium levels. For more comprehensive and longer-term monitoring, measuring magnesium levels in whole blood or red blood cells is considerably more effective.


Last update 8.8.2023