Variations in vitreous humor chemical values as a result of instrumentation

Urea nitrogen, glucose, sodium, potassium, and chloride were measured in common vitreous humor samples using a variety of instruments. There was found to be variation in values obtained by the different procedures for each of these constituents. The variation in electrolyte values between the different procedures can pose real problems in attempting to determine the presence of an antemortem dehydration or low salt condition. Possible reasons for these variations are discussed, and the normal range of values of both sodium and chloride for the different instrumentalities is provided. However, variations in values for both urea nitrogen and glucose would not pose any problems of interpretation for forensic science evaluations.