Normal body temperature and the effects of age, sex, ambient temperature and body mass index on normal oral temperature: A prospective, comparative study

Normal oral, rectal, tympanic and axillary body temperature in adult men and women: a systematic literature review The purpose of this study was to investigate normal body temperature in adult men and women. A systematic review of data was performed. Searches were carried out in MEDLINE, CINAHL, and manually from identified articles reference lists. Studies from 1935 to 1999 were included. Articles were classified as (1) strong, (2) fairly strong and (3) weak evidence. When summarizing studies with strong or fairly strong evidence the range for oral temperature was 33.2-38.2 degrees C, rectal: 34.4-37.8 degrees C, tympanic: 35.4- 37.8 degrees C and axillary: 35.5-37.0 degrees C. The range in oral temperature for men and women, respectively, was 35.7-37.7 and 33.2-38.1 degrees C, in rectal 36.7-37.5 and 36.8-37.1 degrees C, and in tympanic 35.5-37.5 and 35.7-37.5 degrees C. The ranges of normal body temperature need to be adjusted, especially for the lower values. When assessing body temperature it is important to take place of measurement and gender into consideration. Studies with random samples are needed to confirm the range of normal body temperature with respect to gender and age.

Women differ from men in thermal responses to exogenous heat load and heat loss as well as to endogenous heat load during exercise, because they usually have a larger ratio of body surface to body mass, a greater subcutaneous fat content, and lower exercise capacity. When these differences are eliminated in experimental studies, it appears that women's sweating response to heat load is still smaller than that of men, but they are able to maintain their core body temperature on a similar level to that of men as a result of greater evaporative efficiency of sweating. In addition, the changing rate of sex hormone release during the menstrual cycle modifies thermoregulation in women, so there are differences in resting body temperature and thermal responses to positive or negative heat loads depending on the phase of the cycle. In this review, the changes in thermoregulation in young women taking oral contraceptives and those associated with the menopause and hormonal replacement therapy are also described.

Immunosenescence results in populating immune tissues with less functional T cells, and perhaps B cells dendritic cells, that do not function well and produce more type 2 cytokines and fewer type 1 cytokines. Impaired immunity, distinct from immunosenescence, correlates more with disease burden than chronologic age. Older adults who have chronic diseases or chronic infections are more susceptible to common infections and have poor vaccine responses. Understanding specific mechanisms and targeting interventions are dependent on research to resolve the relationship between frailty-associated impaired immunity and the role of chronic infection versus immunosenescence in developing impaired immunity.