From the Guidelines
Normal body temperature in Celsius is approximately 37°C, with a range that can vary due to several factors such as age, gender, and diurnal variation. According to the most recent guidelines from the Society of Critical Care Medicine and the Infectious Diseases Society of America 1, the normal body temperature range is subject to various factors. The United States Centers for Disease Control and Prevention defines fever as a measured temperature of greater than 38°C 1. It's essential to note that temperature can vary slightly throughout the day, usually being lowest in the early morning and highest in late afternoon or evening. Some key points to consider when evaluating body temperature include:
- The normal body temperature has been decreasing in the human population by 0.03°C per birth decade over the last 157 years 1
- Different definitions of fever exist for various populations, such as individuals greater than 65 years old residing in long-term care facilities, where fever is defined as a single oral temperature greater than 37.8°C 1
- Factors such as physical activity, environmental conditions, menstrual cycles, and age can cause minor fluctuations in body temperature The precise regulation of body temperature is crucial for optimal enzyme function and cellular processes in the body, and any significant deviation from the normal range can have implications for morbidity, mortality, and quality of life.
From the Research
Normal Body Temperature
The normal body temperature in Celsius is a topic of discussion in various studies.
- According to 2, in normal healthy adults, oral temperature is estimated to vary between 36.1°C and 37.2°C.
- A study by 3 found that the mean temperature across all participants was 36.1°C, which is lower than most studies have reported.
- Another study by 4 calculated the ranges (mean ± 2 standard deviations) for different measurement sites, including:
- Rectal: 36.32-37.76°C
- Tympanic: 35.76-37.52°C
- Urine: 35.61-37.61°C
- Oral: 35.73-37.41°C
- Axillary: 35.01-36.93°C
- The study by 5 suggests that body temperature should be evaluated in relation to individual variability, and that the best approach is to use the same site and an unadjusted mode without adjustments to other sites.
- It is also noted by 3 that using a standardized "normal" temperature can lead to errors for many people, and that individual differences are simply too great, highlighting the need for personalizing body temperature.