A body found with a vitreous sodium of 138 mmol/L and vitreous chloride of 105 mmol/L, and serum sodium of 188 mmol/L is examined. The MOST likely explanation for this discrepancy is:

• A Postmortem imbibition and haemolysis causing false elevation of serum sodium ✓
• B Antemortem hypernatraemia with artefactual postmortem haemodilution in blood
• C Antemortem sodium depletion with postmortem diffusion of sodium into vitreous
• D Vitreous sodium is unreliable and the serum value is more accurate

Explanation

Postmortem serum electrolytes are profoundly altered by haemolysis, putrefaction, and redistribution of intracellular ions. Vitreous sodium and chloride are far more resistant to postmortem artefact and closely reflect antemortem levels. The elevated serum sodium (188 mmol/L) with normal vitreous sodium (138 mmol/L) is a classic example of postmortem haemolysis causing false elevation of apparent serum sodium through release of intracellular contents. Antemortem hypernatraemia would be reflected in both compartments.

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

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