Perioperative Temperature Monitoring: Reply

Commenting on our review, Nelson writes that “extensive cohort studies indicate [body temperature] is closer to 36.5°C” than 37°C.1 The review indeed specified “normal human core body averages about 37°C,” and “there a superimposed circadian rhythm with roughly 1°C range.”2 “Normal temperature thus varies from ≈36.5°C (usually 3:00 am) ≈37.5°C pm). In premenopausal women, there are also changes in the menstrual cycle, being 0.5°C greater during luteal phase.”Nelson cites two support an average of 36.5°C. one them, Gurven et al.3 present study which somewhat implausibly decreased ~0.5°C over just 16 yr. However, third way through, measurement changed mercury-in-glass oral thermometers, reasonably accurate, infrared aural canal not. other cited, Protsiv al.,4 more convincing describes large cohort, 2007 through 2017, temperatures were estimated digital thermometers. was 36.7°C men 36.8°C women. Importantly, though, electronic 0.25°C below true temperature.5 Protsiv’s report perfectly consistent very close 37°C.There have been several measured time ingested capsules accurately temperature. Core reported these 37.1 ± 0.1°C,6 36.8 0.3°C,7 0.1°C.8There not single temperature.” Instead, between age, cycle. available evidence indicates 37°C reasonable estimate normal humans.The authors declare no competing interests.