Algor mortis (post-mortem cooling) typically results in a body temperature drop of approximately how many degrees Celsius per hour in a standard environment?

Explanation

## Algor Mortis: Rate of Post-Mortem Cooling **Key Point:** Algor mortis is the post-mortem loss of body heat. The rate of cooling follows a predictable pattern and is used to estimate the post-mortem interval (PMI). ### Rate of Temperature Drop **High-Yield:** Under standard environmental conditions (ambient temperature ~20–25°C), the body loses approximately **0.5–1°C per hour** (commonly cited in standard forensic medicine texts including Parikh's and Modi's). Some modern references quote up to 1–1.5°C per hour, but the classical and most widely tested figure for NEET PG / INI-CET purposes is **0.5–1°C per hour**. Options citing 2–3°C/hr, 3–4°C/hr, or 4–5°C/hr are far too rapid and are not supported by any standard forensic medicine textbook. ### Factors Affecting Algor Mortis Rate | Factor | Effect on Cooling Rate | |--------|------------------------| | **Environmental temperature** | Cold environment → faster cooling; warm environment → slower cooling | | **Body composition** | Obese bodies → slower cooling (insulation); lean bodies → faster cooling | | **Clothing and covering** | Insulation slows cooling | | **Cause of death** | Fever/sepsis → initially faster cooling; hypothermia → slower cooling | | **Ambient humidity** | Affects evaporative cooling | **Clinical Pearl:** Algor mortis is **NOT linear**. The body cools rapidly in the first 8–12 hours, then more slowly as it approaches ambient temperature (asymptotic sigmoid curve). The rate is most reliable between 6–24 hours post-mortem. **Mnemonic:** **ALGOR = A**pprox **0.5–1°C/hr** (standard rate) → **L**oss of heat → **G**radual cooling → **O**ver 8–12 hrs rapid → **R**ate slows near ambient. ### Henssge Nomogram The Henssge nomogram is a graphical tool used to estimate PMI based on: - Rectal temperature - Ambient temperature - Body weight - Clothing/covering - Environmental factors It accounts for the non-linear nature of cooling and provides a more accurate PMI estimate than simple arithmetic. ### Limitations of Algor Mortis for PMI Estimation - High variability due to individual and environmental factors - Unreliable in first 2–3 hours (temperature drop is minimal) - Unreliable after 24 hours (body temperature approaches ambient) - Most useful between 6–24 hours post-mortem [cite: Parikh's Textbook of Medical Jurisprudence & Toxicology, Ch 3; Modi's Medical Jurisprudence & Toxicology]