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Forensic Medicine · Thanatology
Sample itemA pathologist wants to estimate time since death in the first day or two using a biochemical measurement. Which is the most useful?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
D. Vitreous potassium level
After death potassium leaks from cells into the vitreous humour at a fairly steady rate, so its concentration rises with time and is relatively protected from early post-mortem changes. This helps estimate the post-mortem interval.
Option by option
A. Blood urea nitrogen
Blood urea nitrogen stays stable after death and does not track time.
B. Blood alcohol concentration
Blood alcohol reflects intake and metabolism, not time since death.
C. Serum creatinine
Serum creatinine remains stable and does not help.
D. Vitreous potassium level (correct)
Vitreous potassium rises progressively after death, making it a time indicator.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.