Evaluation of glucose determination in untreated serum samples. Clin Chem

rns LABORATORY has adopted the collection of blood samples in evacuated tubes1 without anticoagulant in order to provide a uniform method of collection by both the laboratory and the clinical staff for biochemical determinations. The current study was made to deter-mine whether serum obtained by this method of collection was capable of yielding accurate glucose analyses. Glucose values from untreated serum samples collected by vacuum were compared with the plasma glucose values obtained by vacuum collection over sodium fluoride, since sodium fluoride has wide acceptance as an antiglycolytic agent (1). PROCEDURE Two separate blood samples were collected at the same time by the Vacutainer method for glucose analysis. Plasma from one tube, con-taining 50 mg. of sodium fluoride and 5 mg. of thymol, and serum without added preservative from the tube containing clotted blood were analyzed at the same time for glucose by the Nelson-Somogyi method (2). Two hundred samples were analyzed by this procedure. Usually blood samples remain at room temperature in the labora-tory for about one hour between the time of collection and protein precipitation. This interval includes the time required to collect many specimens in a large hospital and the time required for the necessary clerical work before processing