SerumNatrium

SerumNatrium is the concentration of sodium ions in blood serum, typically measured in millimoles per liter (mmol/L). Sodium is the major extracellular cation and a key determinant of extracellular fluid volume, nerve impulse transmission, and muscle function. SerumNatrium is routinely reported as part of standard electrolyte panels in clinical laboratories.

Normal values are influenced by age and the method used, but in healthy adults the common reference range is roughly 135 to 145 mmol/L. SerumNatrium reflects water balance more than sodium intake; shifts in serum concentration often indicate disorders of water retention or loss rather than a primary sodium disorder.

Measurement is performed on serum or plasma using indirect or direct ion-selective electrode methods on automated analyzers. Preanalytical factors such as hemolysis, lipemia, or high protein can influence results with some assay platforms. Pseudohyponatremia may occur with severe lipemia or paraproteinemia when indirect measurement is used.

Clinical interpretation associates SerumNatrium with several disorders. Hyponatremia (serum sodium below 135 mmol/L) can reflect excess water relative to sodium due to SIADH, heart failure, liver cirrhosis, or volume depletion. Hypernatremia (above 145 mmol/L) generally indicates free-water loss or inadequate water intake. Severe shifts may cause confusion, seizures, or coma.

Clinical interpretation should consider confounders such as glucose level, which can distort sodium concentration; a correction for hyperglycemia is sometimes applied. Serum osmolality and urine sodium further aid in distinguishing causes. Management decisions depend on the underlying etiology and tempo of change, with careful avoidance of rapid correction to minimize neurological risk.

SerumNatrium is a core laboratory parameter in medicine. While the value provides important clues about fluid status and electrolyte balance, it should be interpreted in the context of clinical presentation and additional laboratory data.