Natriumkoncentration

Natriumkoncentration refers to the amount of sodium ions (Na+) in a given volume of solution, most commonly expressed as millimoles per liter (mmol/L) or milliequivalents per liter (mEq/L). In human physiology, natriumkoncentration is typically described for extracellular fluid and blood plasma, where sodium is the principal extracellular cation and contributes substantially to the osmolality of body fluids.

In adults, the normal serum sodium concentration is about 135–145 mmol/L, though reference ranges may vary by laboratory. The total body sodium content is linked to extracellular fluid volume and body water, and changes in sodium balance influence fluid distribution between bodily compartments.

Regulation of natriumkoncentration is achieved mainly through the kidneys and related hormonal systems. Aldosterone increases sodium reabsorption in the distal nephron, while antidiuretic hormone modulates water retention and thereby concentrates or dilutes sodium. The renin–angiotensin–aldosterone system and natriuretic hormones also play roles in sodium excretion or conservation, with dietary intake shaping long‑term balance.

Clinical relevance and measurement commonly focus on serum/plasma natriumkoncentration. Abnormal levels indicate dysnatremia: hyponatremia (<135 mmol/L) or hypernatremia (>145 mmol/L). Hyponatremia can result from excess water, SIADH, heart, liver, or kidney disease, or diuretic use; hypernatremia from excessive water loss, diabetes insipidus, or high sodium intake. Rapid shifts in sodium can cause serious neurologic complications.

Laboratory assessment may also include urine sodium concentration to evaluate renal handling, and calculations of plasma osmolality to interpret complex or mixed disturbances.