CORE BODY-TEMPERATURE IS NORMAL IN CHRONIC-FATIGUE-SYNDROME

Background: Subjects with chronic fatigue syndrome (CFS) frequently re port symptoms of subnormal body temperature and low-grade fever. We co nducted a study to determine whether CFS subjects manifest any abnorma lity of core body temperature (CBT) that might help explain their fati gue. Methods: Continuous 24-hour recordings of CBT measured every 5 mi n were performed in 7 subjects meeting the Centers for Disease Control definition of CFS. Three additional groups were studied: normal contr ols, subjects with seasonal allergy, and subjects with major depressio n. Subjects (n = 7) in each group were age-, sex-, and weight-matched to the CFS group and had normal basal metabolic rates, thyroid functio n, and 24-hour urinary free cortisol excretions. CBT was measured with an ingestible radio frequency transmitter pill and a belt-worn receiv er-logger. Each pill was factory-calibrated to +/- 0.1 degrees C and f ield-calibrated with a water bath calibration prior to use. Results: T he 24-hour mean calibration-adjusted CBTs of each group were not signi ficantly different (control: 37.00 +/- 0.17 degrees C; CFS: 37.04 +/- 0.31 degrees C; allergy: 37.15 +/- 0.18 degrees C; depression: 37.26 /- 0.18 degrees C). Similarly, the mean peak and trough circadian temp eratures were not statistically different The mean 24-hour profile of CBT for each group showed a similar circadian rhythm. In simultaneousl y collected blood samples, each group showed a similar circadian profi le of serum cortisol with a peak occurring at 08:00. Conclusions: Subj ects with CFS have normal CBT despite frequent self-reports of subnorm al body temperature and low-grade fever. (C) 1998 Society of Biologica l Psychiatry.