ISSN: 0022-1198
CODEN: JFSCA
Published Online: 1 May 1998
Page Count: 4

Electrolyte Concentration Differences Between Left and Right Vitreous Humour Samples
Pounder, DJ
Professor of forensic medicine, research assistant, research student and research fellow, University of Dundee,

Carson, DO
Professor of forensic medicine, research assistant, research student and research fellow, University of Dundee,

Johnston, K
Professor of forensic medicine, research assistant, research student and research fellow, University of Dundee,

Orihara, Y
Professor of forensic medicine, research assistant, research student and research fellow, University of Dundee,

(Received 30 July 1997; accepted 5 September 1997)

Abstract

Between-eye differences in electrolyte concentrations were studied in 200 medico-legal autopsies using an ion-specific electrode system. Taking the highest of the paired vitreous potassium concentrations, cases <15 mM/L were classified as biochemically nonputrefied (Cat.1, n = 124), cases 15 to 20 mM/L as early putrefaction (Cat.2, n = 51), and cases >20 mM/L as biochemically putrefied (Cat.3, n = 25). Mean paired vitreous sodium for all cases (n = 200) was 112 to 173 mM/L (mean 148, standard deviation (SD) = 8.9); between-eye differences were 0 to 8 mM/L (0% to 5.1% of mean), averaging 1.5 mM/L (1%) and with only one case (in Cat.3) outside instrument accuracy (±3 mM/L). Mean paired vitreous chloride for all cases was 73 to 124 mM/L (mean 109, SD = 7.8); between-eye differences were 0 to 9 mM/L (0% to 8.8% of mean), averaging 1.7 mM/L (1.5%) and with 5 of 200 cases outside instrument accuracy (±3 mM/L). Thus between-eye concentration differences of sodium and chloride are tolerable using this methodology. Previous reports of greater variability likely reflect errors introduced by sample manipulation prior to analysis. By contrast, between-eye differences in potassium in Cat.1 cases were 0 to 2.34 mM/L (0% to 21.8% of mean) averaging 0.37 mM/L (3.3%). Significant and erratic between-eye differences in potassium undermine the usefulness of vitreous potassium in estimation of time of death.

Keywords:
forensic science, forensic pathology, forensic technology, vitreous humour, autopsy, electrolytes, time of death, sodium, chloride, potassium, calcium, pH

Paper ID: JFS16187J
DOI: 10.1520/JFS16187J
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