Prognostic value of plasma and urine paraquat concentration.

A non-exponential mathematical equation was used to extrapolate the 'predictive line' for plasma paraquat concentrations beyond 24 h. Plasma paraquat concentrations were measured in 30 patients who were admitted more than 24 h after overdose. The extrapolated line accurately predicted the outcome in 27 of these 30 patients. Urine paraquat concentrations were measured in 53 patients. All patients with urine paraquat concentrations of less than 1 mg/l (colourless or light blue test result using the colorimetric test) within 24 h of overdose survived. In contrast, patients with urine paraquat concentrations of more than 1 mg/l had a high probability of death. Even if plasma paraquat concentrations have a higher predictive value, urine data may contribute to a more rapid evaluation of prognosis.