Comparative Study Evaluating the Accuracy of the Urine Sodium Dithionite Test to Predict Plasma Paraquat Concentration in Poisoning Cases

ABSTRACT

PURPOSE: Plasma Paraquat level is one of the most important prognostic factors used in identifying Paraquat poisoning. Urine sodium dithionite tests are widely used in clinical settings for detecting the presence of Paraquat chemicals and predicting prognosis, but this test is subjective and qualitative. In this prospective study, we evaluated the correlation between sodium dithionite test results as measured by a colorimeter, versus actual plasma or urine Paraquat levels. METHODS: Plasma and urine sample were taken from patients upon arrival at a local emergency center (ED) within 12 hours after Paraquat ingestion. Urine was tested using sodium dithionite reaction and the resulting urine color was measured by colorimeter to result in an L (lightness) value. RESULTS: A total of 23 patients were enrolled in this study with a mean age of 57 years old, mean Paraquat intoxication volume of 94 mL, and mean Paraquat intoxication prior to ED arrival of 3.2 hours. The patients' mean blood Paraquat concentration was 82.23 microg/ml and urine Paraquat concentration was 169.19 microg/ml. Using the sodium dithionite test, 17 patients were diagnosed as beyond 'strong positive'. L values were correlated with intoxication volumes, blood Paraquat concentrations, and urine Paraquat concentrations. Blood Paraquat concentrations showed significant correlation with L value, poison volume, urine Paraquat volume, and creatinine values. CONCLUSION: The greater the intoxicated Paraquat volume, blood Paraquat concentration, and urine Paraquat concentration, the lower the L value.