Plasma norepinephrine kinetics in patients with posttraumatic stress disorder.

To determine whether basal sympathetic nervous system (SNS) function is increased in patients with posttraumatic stress disorder (PTSD), we used a radioisotope dilution technique to assess basal arterialized plasma norepinephrine (NE) kinetics in 12 men who were Viet Nam combat veterans with PTSD and six normal controls. In addition to determining the rates of appearance of NE into, and clearance of NE from, plasma, we measured basal arterialized plasma levels of epinephrine (EPI), and also vital signs, in both groups. Patients with PTSD actually manifested lower arterialized plasma levels of NE, and had lower rates of appearance of NE into plasma, than did controls. The rate of NE clearance from plasma was unaltered in PTSD patients. Patients with PTSD also showed a trend toward lower arterialized EPI levels than controls, but manifested a trend toward higher diastolic blood pressure. Our data indicate that basal SNS activity is not increased in patients with PTSD and that previous reports of increased resting SNS activity in this population may instead reflect SNS reactivity.