BACKGROUND: Subjects with chronic fatigue syndrome (CFS)
frequently report symptoms of subnormal body temperature and
low-grade fever. We conducted a study to determine whether CFS
subjects manifest any abnormality of core body temperature
(CBT) that might help explain their fatigue.
Continuous 24-hour recordings of CBT measured every 5 min were
performed in 7 subjects meeting the Centers for Disease
Control definition of CFS. Three additional groups were
studied: normal controls, subjects with seasonal allergy, and
subjects with major depression. Subjects (n = 7) in each group
were age-, sex-, and weight-matched to the CFS group and had
normal basal metabolic rates, thyroid function, and 24-hour
urinary free cortisol excretions. CBT was measured with an
ingestible radio frequency transmitter pill and a belt-worn
receiver-logger. Each pill was factory-calibrated to +/- 0.1
degree C and field-calibrated with a water bath calibration
prior to use.
RESULTS: The 24-hour mean calibration-adjusted
CBTs of each group were not significantly different (control:
37.00 +/- 0.17 degrees C; CFS: 37.04 +/- 0.31 degrees C;
allergy: 37.15 +/- 0.18 degrees C; depression: 37.16 +/- 0.18
degrees C). Similarly, the mean peak and trough circadian
temperatures were not statistically different. The mean
24-hour profile of CBT for each group showed a similar
circadian rhythm. In simultaneously collected blood samples,
each group showed a similar circadian profile of serum
cortisol with a peak occurring at 08:00.
with CFS have normal CBT despite frequent self-reports of
subnormal body temperature and low-grade fever.