Keywords: fever, infection, physiology (PubMed Search)
Older patients are less likely than their younger counterparts to mount a fever in response to an infection. One explanation is that their basal temperature is lower. Some experts suggest redefining fever in older patients to match this decrease of 0.15C per decade. Therefore, your 80 year old patient would be considered “febrile” if their temperature is above 37.3C, rather than the traditional 38C.
Roghmann MC, Warner J, Mackowiak PA. The relationship between age and fever magnitude. Am J Med Sci. 2001;322(2):68-70