Twenty-four hour growth hormone secretion in patients with panic disorder.
BACKGROUND
Patients with panic disorder have blunted growth hormone (GH) responses to clonidine, suggesting subsensitivity of post-synaptic alpha(2)-adrenoreceptors, presumably in response to excessive central noradrenergic outflow. However, basal levels of GH release over a full circadian cycle have not been examined in panic. Reduced basal GH release would suggest an overall hypo-active GH system rather than a specific alpha-adrenergic abnormality.


METHODS
To determine whether panic patients show reduced basal GH secretion, 20 patients and 12 healthy controls were studied. Blood samples were drawn every 15 min for 24 h and plasma was assayed for GH. Patients were restudied during successful treatment with alprazolam. Groups were compared on overnight and daytime GH secretion and circadian patterns of release.


RESULTS
Patients showed normal levels on all measures of GH release. Treatment may have reduced nocturnal GH release slightly, but treated patients still did not differ from controls. The normal predominance of sleep over waking GH secretion was seen in both groups.


CONCLUSIONS
Panic patients, in contrast to depressed patients, have normal somatotrophic axis activity when measured in a resting state over a full circadian cycle. GH dysregulation may only be evident in these patients in activation paradigms and has been most consistently demonstrated by challenges with the alpha(2)-noradrenergic agonist, clonidine.
Abelson
James L
JL
Department of Psychiatry, University of Michigan, Anxiety and Stress Disorders Program, 1500 E. Medical Center Drive, Ann Arbor, MI 48109-0118, USA. jabelson@umich.edu
Curtis
George C
GC
Uhde
Thomas W
TW
D000328:Adult; D000525:Alprazolam / Q000627:therapeutic use; D014151:Anti-Anxiety Agents / Q000627:therapeutic use; D002940:Circadian Rhythm / Q000502:physiology; D005260:Female; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D008297:Male; D016584:Panic Disorder / Q000097:blood*; D011569:Psychiatric Status Rating Scales; D011863:Radioimmunoassay
D014151:Anti-Anxiety Agents; D019382:Human Growth Hormone; D000525:Alprazolam