Stabilization of blood glucose by cooling with ice: an effective procedure for preservation of samples from adults and newborns.

Glycolysis causes a considerable decrease in blood glucose when whole blood is kept at room temperature without preservative. The most commonly used preservative, NaF, makes analysis of other serum constituents such as sodium and calcium and urea difficult or impossible, an especially serious limitation when sample size must be restricted. In samples at room temperature without preservative, plasma glucose decreased 36 mg/liter per hour in blood from adults and 60 mg/liter per hour in blood from newborns. Cooling on ice slowed these rates to 3.9 and 11, respectively. Plasma potassium increased 0.3 mmol/liter per hour in cooled specimens from both adults and newborns. Sodium, calcium, chloride and urea values were unaffected. We conclude that cooling effectively stabilizes plasma glucose for 4 h in samples from both adults and newborns and that potassium may be measured with negligible change for as long as 1 h and other constituents for the entire period.