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Sodium in the blood

Alexey Portnov, medical expert
Last reviewed: 23.04.2024

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The reference values (norm) of the concentration of sodium in the blood serum are 135-145 mmol / l (meq / l).

In the body of a healthy person with a body weight of 70 kg contains 3,500 mmol or 150 g of sodium. 20% of this amount is concentrated in the bones and does not directly participate in the metabolism. The largest part of sodium is almost completely in the liquid of the extracellular space.

Sodium is the main cation of extracellular fluid, where its concentration is 6-10 times higher than inside the cells. Physiological value of sodium is to maintain the osmotic pressure and pH in the intracellular and extracellular spaces, it affects the processes of nervous activity, the state of the muscular and cardiovascular system and the ability of tissue colloids to "swell."

Sodium is excreted by the kidneys (with urine), GIT (with feces) and skin (with sweat). The excretion of sodium by the kidneys varies in a wide range: 1-150 mmol / day. With feces, 1-10 mmol / day is lost. The concentration of sodium in the sweat is 15-70 mmol / l.

Renal mechanism of sodium regulation is the most important factor in maintaining its normal concentration in blood plasma. Many causes of hyponatremia and / or hypernatremia are associated with impaired renal function.

A significant increase or decrease in the sodium content in the blood serum comes as a result of disproportionate losses of water and salts. With these conditions, there may be a need for emergency care.

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