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document
Growth hormone ( GH ) responses to GH-releasing hormone alone or combined with arginine in patients with adrenal incidentaloma : evidence for enhanced somatostatinergic tone . Spontaneous and stimulated GH secretion is blunted in hypercortisolemic states due to increased hypothalamic somatostatinergic tone . However , no data are available on the characteristics of GH secretion in patients with incidentally discovered adrenal adenomas . They represent an interesting model for studying GH secretion , as a slight degree of cortisol excess may frequently be observed in such patients who do not present with any clear Cushingoid sign . In the present study , 10 patients ( 3 men and 7 women , aged 48-63 yr ) with an adrenal mass discovered serendipitously underwent , on separate occasions , a GHRH injection alone or combined with an infusion of the functional somatostatin antagonist , arginine . Thirteen age-matched healthy volunteers served as controls . Briefly , arginine ( 30 g ) was infused from -30 to 0 min , and GHRH ( 100 microg ) was injected as a bolus at 0 min , with measurement of serum GH [ immunoradiometric assay ( IRMA ) ] every 15 min for 150 min . Plasma IGF-I ( RIA after acid-ethanol extraction ) was measured in a morning sample . The diagnosis of cortical adenoma was based on computed tomography features and pattern of uptake on adrenal scintigraphy . Patients with obesity and/or diabetes were excluded . The study design included also an endocrine work-up aimed to study the hypothalamic-pituitary-adrenal axis [ urinary free cortisol ( UFC ) excretion , serum cortisol at 0800 h , plasma ACTH at 0800 h , morning cortisol after overnight 1 mg dexamethasone ] . Five of 10 patients showed abnormalities of the hypothalamic-pituitary-adrenal axis , including borderline or increased UFC excretion in 4 of them accompanied by blunted ACTH in 2 cases and failure of cortisol to suppress after dexamethasone in 1 ; the fifth patient displayed low ACTH and resistance to dexamethasone suppression . However , all patients had a unilateral uptake of the tracer on the side of the mass with suppression of the contralateral normal adrenal gland . As a group , the patients displayed greater UFC excretion and lower ACTH concentrations than the controls . GH release after GHRH treatment was blunted in patients bearing adrenal incidentaloma compared with controls ( GH peak , 5.7 +/- 5.2 vs. 18.0 +/- 7.0 microg/L ; P < 0.0001 ) , whereas GHRH plus arginine was able to elicit a comparable response in the 2 groups ( GH peak , 33.5 +/- 20.3 vs. 33.7 +/- 17.5 microg/L ; P = NS ) . The ratio between GH peaks after GHRH plus arginine and after GHRH plus saline was significantly greater in patients than in controls ( 751 +/- 531 % vs. 81 +/- 45 % ; P = 0.0001 ) . Similar data were obtained when comparing GH area under the curve after GHRH plus saline or GHRH plus arginine between the 2 groups . In summary , the present data suggest that in patients with incidental adrenal adenomas the GH response to GHRH is blunted due to increased somatostatinergic tone , as it can be restored to normal by pretreatment with the functional somatostatin antagonist arginine . The blunted GH release to GHRH may be an early and long lasting sign of autonomous cortisol secretion by the adrenal adenoma .
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Intervention_Physical
GH-releasing hormone alone
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Intervention_Physical
combined with arginine
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Intervention_Pharmacological
GHRH injection alone
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Intervention_Control
controls
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Intervention_Pharmacological
arginine ( 30 g )
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Intervention_Pharmacological
GHRH ( 100 microg )
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Intervention_Physical
serum GH [ immunoradiometric assay ( IRMA ) ]
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Intervention_Physical
Plasma IGF-I ( RIA after acid-ethanol extraction )
3094
Intervention_Control
GHRH treatment
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Intervention_Pharmacological
GHRH plus arginine
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Intervention_Pharmacological
GHRH plus arginine
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Outcome_Physical
Growth hormone ( GH ) responses
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Outcome_Physical
hypothalamic-pituitary-adrenal axis [ urinary free cortisol ( UFC ) excretion
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Outcome_Physical
serum cortisol at 0800 h
3100
Outcome_Physical
plasma ACTH at 0800 h
3101
Outcome_Physical
morning cortisol after overnight 1 mg dexamethasone
3102
Outcome_Physical
abnormalities of the hypothalamic-pituitary-adrenal axis
3103
Outcome_Physical
borderline or increased UFC excretion
3104
Outcome_Physical
UFC excretion
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Outcome_Physical
lower ACTH concentrations
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Outcome_Physical
GH release after GHRH treatment
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Outcome_Other
GH peaks after GHRH plus arginine
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Outcome_Other
GHRH plus saline
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Outcome_Physical
GH response
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Outcome_Physical
somatostatinergic tone
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Participant_Condition
adrenal incidentaloma
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Participant_Condition
adrenal adenomas .
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Participant_Sample-size
10
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Participant_Sample-size
3
3115
Participant_Sex
men
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Participant_Sample-size
7
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Participant_Sex
women
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Participant_Age
48-63 yr
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Participant_Sample-size
Thirteen
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Participant_Condition
healthy volunteers
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Participant_Condition
controls
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Participant_Condition
obesity and/or diabetes were excluded
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Participant_Condition
adrenal incidentaloma
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Participant_Condition
incidental adrenal adenomas