How long should a mercury thermometer be kept under the armpit?
Jan 09, 2025
Source: Cainiu Health
Dr. Ren Yi
Introduction
Under normal circumstances, a mercury thermometer needs to be placed under the armpit for more than 5 minutes. If necessary, it is recommended to follow the guidance of a healthcare professional. When placing the mercury thermometer under the armpit, it must reach thermal equilibrium with the underlying tissues to accurately measure the body's core temperature. The skin, fat, and muscle tissues in the armpit area themselves have a certain thickness and thermal capacity.
Under normal circumstances, a mercury thermometer needs to be placed under the armpit for more than 5 minutes. If necessary, it is recommended to follow the guidance of a healthcare professional. Detailed explanation is as follows:
When placing a mercury thermometer under the armpit, the thermometer must reach thermal equilibrium with the underlying tissue to accurately measure the body's core temperature. The skin, fat, and muscle tissues in the armpit area have a certain thickness and heat capacity, so it takes time for heat to transfer from the body's interior to the mercury column in the thermometer. This process requires more than 5 minutes for the mercury column to rise to a level corresponding to the body temperature, thereby accurately displaying the core body temperature.
If the measurement duration is too short, the thermometer may not fully absorb the body's heat, resulting in a temperature reading lower than the actual body temperature, leading to inaccurate results and potential errors.
Before taking the measurement, one should avoid strenuous exercise, drinking hot beverages, consuming spicy foods, or drinking alcohol, as these may temporarily elevate body temperature and affect the measurement accuracy.
