Validation of Fluoride Oxalate against Iodide Oxalate, Chloride Oxalate, and Glucomedics Anticoagulants for Glucose Estimation

OBJECTIVE: Accurate measurement of glucose is critical for diabetic care. Sodium fluoride/potassium oxalate (NaF/KOx) has been the preferred tube for measuring glucose. The pre-analytical challenges associated with the use of NaF/KOx and the emergence of COVID-19 presented challenges in the purchase of preservatives for measuring glucose. The need to validate other available and accessible local preservatives for measuring glucose becomes necessary. This study aimed to validate glucose values obtained using standard NaF/KOx anticoagulant against iodide oxalate, chloride oxalate, and glucomedics anticoagulant. METHODS: Blood samples were collected from 45 apparently healthy individuals and distributed into four tubes: NaF/KOx, sodium chloride/potassium oxalate (NaCl/KOx), iodide oxalate/potassium oxalate (IOx/KOx), and glucomedics. Samples were separated into aliquots and stored for various durations before centrifugation. Glucose analysis was measured using the glucose oxidase-peroxidase method. Statistical analysis included bias comparison, mean concentration comparison, Deming’s regression, and Bland-Altman analysis. RESULT: There was a significant decrease in glucose concentration with increasing separation time. Glucomedics showed minimal decrease, exhibited the least bias in all the time points considered with only 1-hour delayed measurement having a clinically acceptable bias of 1.62<2.2%; and demonstrated the strongest correlation with other methods. Mean concentration differences were comparable between glucomedics and NaF/KOx. CONCLUSION: The three different anticoagulants could be a good replacement for NaF/Kox. However, glucose values obtained using glucomedics could give a better clinically useful result than others when a delay in sample processing is inevitable. The need to consider the use of any of the anticoagulants in place of NaF/KOx is strongly recommended.