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Magnesium in the blood

Alexey Portnov, medical expert
Last reviewed: 20.11.2021

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Magnesium is the fourth most element in the human body after potassium, sodium, calcium and the second most abundant element in the cell after potassium. The human body contains about 25 g of magnesium, 60% of it is part of the bone tissue, and most of the rest of the stock is in cells. Only 1% of the total magnesium is contained in the extracellular fluid. Approximately 75% of the magnesium of the serum is in ionized form, 22% is associated with albumin and 3% - with globulins. Magnesium plays an important role in the functioning of the neuromuscular apparatus. The largest content of magnesium in the myocardium. Physiologically, magnesium is a calcium antagonist, its deficiency in the serum is accompanied by an increase in the calcium content. The higher the metabolic activity of the cell, the more magnesium it contains. The concentration of ionized magnesium in the cell is maintained at a constant level even with large fluctuations in the extracellular fluid.

trusted-source [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]

The concentration of magnesium in the blood serum

Age	Concentration of magnesium in blood serum
Age	Meq / liter	Mmol / l
Newborns	1.0-1.8	0.5-0.9
5 months - 6 years	1.32-1.88	0.71-0.95
6-12 years old	1.38-1.74	0.69-0.87
12-20 years old	1.35-1.77	0.67-0.89
Adults	1.3-2.1	0.65-1.05

Magnesium is a cofactor of a number of enzymatic reactions, it acts as a physiological growth regulator, supporting a stock of purine and pyrimidine bases. Magnesium is necessary at all stages of protein synthesis.

The main regulator for maintaining the concentration of magnesium in the blood serum is the kidney. In a healthy person, the daily magnesium excretion is approximately 100 mg. With the depletion of magnesium, its excretion decreases or ceases altogether. Excess magnesium is rapidly removed by the kidneys. Magnesium passes through the glomerular membrane, 80% of it is reabsorbed in the proximal tubules of the ascending segment of the Henle loop. Large doses of PTH contribute to a decrease in the excretion of magnesium in the urine (glucagon and calcitonin have the same effect). Vitamin D and its metabolites increase the absorption of magnesium in the small intestine, but to a lesser extent than calcium.

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