Chloride
What it measures, and what changes the number.
Chloride is an electrolyte, a charged mineral that helps maintain fluid balance and the acid-base balance of the blood. The test measures the concentration of chloride in serum or plasma.
It is almost always reported as part of an electrolyte or metabolic panel with sodium and potassium, since chloride tends to move together with sodium. Urea and creatinine are often on the same panel because kidney function and hydration affect all of these values.
Most labs measure chloride with ion-selective electrodes. With the indirect version of this method, very high blood fats or proteins can distort the result. Hydration status at the time of the draw also influences the number, and delays in separating the sample are less of an issue for chloride than for potassium. Labs may print it as Cloruro.
Often read alongside: Sodium, Potassium, Urea, Creatinine