Spurious values of serum electrolytes due to admixture of intravenous infusion fluids.

Blood samples may be collected subsequent to the establishment of a working i.v. line. When collected incorrectly, such blood samples can yield spurious results of serum electrolyte and chemistry determinations. We present such a case and, further, show that serum chemistry values can be altered by contamination with i.v. fluids in the emergency patient and that such alterations can be of sufficient magnitude to affect treatment. Recommendations are given regarding aspiration of blood samples from working i.v. lines to minimize the risk of spurious measurements.