Role of vitreous potassium level in postmortem interval estimation

Background: a consistent rise in the level of vitreous potassium,commencing shortly after death and continuing for 125 hours has been known for 40 years and recommended for the estimation of the time since death. aim: to find out the potassium level in vitreous humor samples taken from the medicolegal autopsy cases and to determine its correlation with the known postmortem interval. methods: in this study 102 vitreous humor samples were collected from medicolegal autopsy cases from the mortuary of forensic medicine and toxicology department,king edward medical university,lahore. analysis was carried out at the department of pathology,kemu,lahore by autoanalyzer using ion selective electrode technique. results: a highly significant linear correlation was observed between the vitreous potassium concentrations with the postmortem interval (r=0.428,p<0.001). the estimated pmi in hours was obtained by using the sturner's equation but it either over estimated or under estimated. the ordinary regression equation was more useful. conclusion: it is established that the postmortem vitreous potassium value can play an important role in estimating the postmortem interval. the ordinary regression equation based upon our own data estimated comparatively more accurate pmi than the well-known sturner's equation.