Use of Chemical Determinations on Vitreous Humor in Forensic Pathology

Abstract

It is frequently important in deciding the cause of death to be able to determine chemical abnormalities which may have existed prior to demise. This is particularly true in cases where clinical history suggests the possibility of such chemical abnormalities, but opportunity for autopsy does not exist. Even when a postmortem examination is done, determination of chemical abnormalities may help establish the cause of death where the autospy findings are inconclusive or may validate the significance of recognizable organ changes. For this reason rather extensive studies have been made in the postmortem chemistry of blood. It has been found that abnormalities in concentrations of protein, calcium, urea nitrogen, creatinine, and bilirubin can be evaluated by study of the serum prior to the onset of intravascular hemolysis. Unfortunately there are many constituents in which postmortem changes occur rapidly and erratically so that extrapolation to probable antemortem values becomes impossible. Serum sodium and chloride concentrations begin to fall soon after death, but the rate of fall varies so markedly from individual to individual that it is impossible to detect electrolyte imbalance except in extreme cases and when the blood has been obtained very soon postmortem. Serum glucose will ordinarily decrease in the left heart and extremital vessels due to continued utilization by the red cells after death, but may be markedly elevated in cases where death results from asphyxia or is accompanied by a large output of epinephrine terminally. Glucose concentrations in blood obtained from the right heart or inferior vena cava frequently are found markedly elevated due to glycogenolysis in the liver but may be low in cases of starvation.

Is the formula of Traub still up to date in antemortem blood glucose level estimation?

“…This results in further mobilisation of liver glycogen and release of glucose into the blood circulation as a counterbalancing phenomenon [18]. Due to the difficulty interpreting postmortem blood glucose levels, other fluids have been proposed as being more reliable in the estimation of antemortem blood glucose concentrations, particularly the cerebrospinal fluid and vitreous humor [19][20][21][22][23][24]. Investigation of the biochemical constituents of the vitreous humor have been periodically performed by several authors [25][26][27].…”

“…However, the postmortem identification of hypoand hyperglycaemia still remains interesting subjects of research. Coe [20,21,23,28] demonstrated that there was a consistent but variable decrease in vitreous glucose concentrations with increasing postmortem time in non-diabetic individuals, whereas postmortem glycolysis had little effect on the elevated vitreous glucose values of uncontrolled diabetics. Given the assumption that glucose is converted into lactate after death and to eliminate the negative effect of postmortem glycolysis, Traub proposed that antemortem blood glucose concentration could be estimated by combining the postmortem values of glucose and lactate found in the cerebrospinal fluid.…”

Vitreous Humor: A Short Review on Post-mortem Applications

“…The normal concentration of lactic acid circulating in the blood is about 1 ± 0.5 mmol/L [43]. Coe's findings show that vitreous values reflect serum values at the moment of death, at least in case of normal or high pre-mortem concentrations [44]. It seems that in the initial period after death (probably up to 6 hours) intensive production of lactates occurs in cytosol [29,41,42].…”

“…VH sodium levels of greater than 155 meq/L have been cited as evidence of dehydration [50]. Although changes occur in post-mortem sodium levels these often remain stable for sufficient time to provide information that may be useful in determining the mechanism of death [26] For example, the ante-mortem serum sodium and chloride concentrations are reflected in post-mortem vitreous values, making it possible to diagnose hyponatremia or hypernatremia at the time of death [1,6,13,14,16,[25][26][27][28]44,49,[51][52][53][54][55][56][57][58][59].…”

Postmortem biochemistry performed on vitreous humor after postmortem CT-angiography

“…Before then, the understanding of these constituents was limited to animals and enucleated human eyes. Subsequently, numerous researchers [4][5][6][7]9,10,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] have performed postmortem biochemical analyses on vitreous humor. These analyses typically focused on levels of vitreous glucose, lactate, sodium, chloride, potassium, urea nitrogen and creatinine.…”