Vitreous potassium concentration as a predictor of postmortem interval: A cross-sectional study among poisoning and burns cases at a tertiary care center in rural Haryana

Background: Time since death (TSD) is an important parameter to the forensic expert. Only a few studies are available in the literature to determine the relationship between vitreous K + concentration and TSD, especially among poisoning and burns cases, and thus information on the same is scant. Therefore the present study was planned. Objective: The main objective was to determine the relationship between changes in vitreous K + concentration with increasing TSD among poisoning and burns cases. An additional objective was to derive a formula for determining TSD from changes in levels of vitreous K + in the study subjects. Materials and Methods: In this study, autopsy cases brought to the mortuary of the Department of Forensic Medicine and Toxicology of a tertiary care center were subjected to collection of vitreous humor for the determination of vitreous K + . Data of 36 cases where autopsy confirmed the cause of death as poisoning or burns were included in this study. Determination of K + level in the collected samples was done by the ion-selective electrode method (Biolyte 2000 autoanalyzer). Results: A linear relationship was observed between vitreous K + concentration and TSD in both the eyes. External factors such as seasonal variations and temperature, gender difference, and age had no appreciable effect on the concentration of vitreous K + in either eye. In this study the linear regression equations obtained from potassium concentration (y) versus time (x) for the two groups among poisoning and burns cases were as follows. For right eye: Regression line (y) = -4.932 x + 1.932; for left eye: Regression line (y) = -5.380 x + 1.990. The K + levels were found to increase up to 40 h after death. Conclusion: This study highlighted the usefulness of the relationship between vitreous potassium concentration and TSD in both the eyes. The formula calculated from the current study could prove to be more appropriate as it is based on more reliable tests