Vitreous Humour Potassium
Definition
Potassium concentration in the eye's vitreous fluid rises linearly with PMI and is one of the more reliable chemical PMI markers up to about 100 hours.
- Body fluid
- Vitreous humour of the eye
- Trend with PMI
- Rises roughly linearly after death
- Useful window
- Up to about 100 hours post-mortem
- Type of marker
- Chemical PMI estimator
Common questions
Why is vitreous fluid preferred over blood for this measurement?+
The eye is anatomically isolated and the vitreous chamber resists bacterial invasion and autolysis longer than blood or other tissues, so potassium leakage from ruptured cells there follows a more predictable, less contaminated curve over time.
Can vitreous potassium alone give a precise time of death?+
No single chemical marker is precise enough on its own. Temperature, individual variation, and sampling technique all affect the potassium curve, so it is used alongside other PMI methods such as the Henssge nomogram rather than in isolation.
Related terms
- Algor Mortis
- Postmortem cooling of the body toward ambient temperature, approximately 1-1.5 degrees Celsius per hour under average conditions. Used alongside other postmortem changes...
- Henssge Nomogram
- A graphical method using rectal temperature, ambient temperature and body weight to estimate PMI within a 95 percent confidence interval, with correction...
- Livor Mortis
- Postmortem pooling of blood in dependent tissues producing a purple-red discolouration. Becomes fixed at roughly 8-12 hours; discordance between liver position and...
- Post-Mortem Interval (PMI)
- The time elapsed between death and discovery or examination of remains. PMI estimation draws on multiple disciplines: soft tissue decomposition stage, insect...
- Rigor Mortis
- The post-mortem stiffening of muscle from ATP depletion and actin-myosin cross-linking. Develops over hours, peaks, and resolves with putrefaction.