At baseline, patients with CFS had a lower number of steps per day, digit span backward score, and urinary cortisol to creatinine ratio. They had a higher fatigue score, heart rate responsiveness, plasma norepinephrine level , and serum C-reactive protein concentration compared with healthy controls. There were no significant differences regarding blood microbiology evaluation.
Adolescent CFS is associated with enhanced sympathetic nervous activity, low-grade systemic inflammation, attenuated hypothalamus-pituitary-adrenal axis function, cognitive impairment, and large activity reduction, but not with common microorganisms. Low-dose clonidine attenuates sympathetic outflow and systemic inflammation in CFS but has a concomitant negative effect on physical activity; thus, sympathetic and inflammatory enhancement may be compensatory mechanisms. Low-dose clonidine is not clinically useful in CFS.