title: Reduced epinephrine reserve in response to insulin-induced hypoglycemia in patients with pituitary adenoma.
abstract: OBJECTIVE
  Hypoglycemia induces rapid secretion of counterregulatory hormones such as catecholamine, glucagon, cortisol, and GH. Insulin-induced hypoglycemia is used for evaluating GH-IGF-I and ACTH-adrenal axes in patients with pituitary disorders. The aim of this study was to determine whether the response of catecholamine secretion to hypoglycemia is disrupted in patients with pituitary adenoma.
  
  
  METHODS
  The study population comprised 23 patients with pituitary adenoma (non-functioning adenoma or prolactinoma). An insulin tolerance test was performed and serum catecholamines as well as plasma GH and serum cortisol were measured.
  
  
  RESULTS
  The study patients showed diminished response of plasma epinephrine to insulin-induced hypoglycemia. With the cutoff level of peak epinephrine for defining severe impairment set at 400 pg/ml, more patients with secondary adrenal insufficiency showed severe impairment of the epinephrine response than did those without it. Peak epinephrine levels to insulin-induced hypoglycemia were significantly correlated with peak cortisol levels. In patients with secondary hypothyroidism, secondary hypogonadism, GH deficiency, or diabetes insipidus, the prevalence of severe impairment of the epinephrine response was similar to that in patients without these deficiencies.
  
  
  CONCLUSIONS
  Impaired epinephrine secretion in response to insulin-induced hypoglycemia was frequently observed in patients with pituitary adenoma. This disorder was especially severe in patients with secondary adrenal insufficiency.
authors.affiliation: Department of Medicine, Osaka University Graduate School of Medicine, Yamada-Oka, Suita, Osaka, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Morita
authors.forename: Michio
authors.initials: M
authors.lastname: Otsuki
authors.forename: Maki
authors.initials: M
authors.lastname: Izumi
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Asanuma
authors.forename: Shuichi
authors.initials: S
authors.lastname: Izumoto
authors.forename: Youichi
authors.initials: Y
authors.lastname: Saitoh
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yoshimine
authors.forename: Soji
authors.initials: S
authors.lastname: Kasayama
mesh_terms: D000236:Adenoma / Q000097:blood* / Q000150:complications / Q000175:diagnosis; D000309:Adrenal Insufficiency / Q000097:blood* / Q000175:diagnosis / Q000209:etiology; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D004837:Epinephrine / Q000097:blood*; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000097:blood* / Q000139:chemically induced; D007004:Hypoglycemic Agents; D007328:Insulin; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D010911:Pituitary Neoplasms / Q000097:blood* / Q000150:complications / Q000175:diagnosis; D015175:Prolactinoma / Q000097:blood / Q000150:complications / Q000175:diagnosis; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers; D007004:Hypoglycemic Agents; D007328:Insulin; D009638:Norepinephrine; D004837:Epinephrine