Which type of sample is typically analyzed for electrolyte levels?

The analysis of electrolyte levels is most commonly performed on serum samples. Serum refers to the liquid portion of blood that remains after the blood has clotted and the clot has been removed. It is important for electrolyte analysis as it provides a clear matrix devoid of cellular components, which could interfere with the measurements. Electrolytes such as sodium, potassium, chloride, and bicarbonate are typically evaluated in serum to assess the body’s fluid balance, acid-base status, and other metabolic functions.

While whole blood can also be used for some type of electrolyte testing, it is less common due to the presence of red and white blood cells and platelets, which can complicate the analysis. Similarly, plasma, the liquid component of blood that includes clotting factors, can be used for electrolyte analysis but is less routine than serum. Urine is typically analyzed for electrolytes like sodium and potassium in the assessment of renal function and fluid balance but does not reflect serum electrolyte levels directly. Therefore, serum is the preferred and most accurate sample type for routine electrolyte level measurements.