M. S. Vivaldi

Frequency of pheochromocytoma in adrenal incidentalomas and utility of the glucagon test for the diagnosis

To investigate the frequency of pheochromocytoma in patients with incidentally discovered adrenal masses (incidentalomas) and to evaluate the sensitivity, specificity and diagnostic accuracy of the Glucagon test in comparison with resting plasma catecholamines, 89 patients with adrenal incidentalomas (age range 23–80 yr; 41 males and 48 females) were studied. Fifty-seven patients were normotensive (SBP 130±1.8 mmHg; DBP 80±0.7 mmHg, mean±SE) and 32 had stable hypertension (SBP 155±3.3 mmHg, DBP 93±1.4 mmHg): no patient complained of typical signs or symptoms of pheochromocytoma. Resting plasma samples for noradrenaline and adrenaline determination and, at appropriate intervals, the Glucagon test (1 mg i.V.), were performed in all subjects. Diagnosis of pheochromocytoma was made on the basis of humoral evaluations and/or surgical intervention in 6 patients (6.7%), of whom 3 hypertensives and 3 normotensives. Resting plasma catecholamines revealed 5 out of 6 patients with pheochromocytoma: in 3 cases both catecholamines were above the normal range, in 1 only adrenaline was elevated and in 1 case only noradrenaline. Similarily, the glucagon test identified 5/6 pheochromocytomas: in 3 patients the response was abnormal for both catecholamines, in 1 only for adrenaline and in 1 case only for noradrenaline. The sensitivity, specificity, and diagnostic accuracy of resting plasma catecholamines and of the glucagon test were comparable: 83.3%, 96.3%, and 95.5%, respectively. In conclusion, the frequency of pheochromocytoma in adrenal incidentalomas is not negligible, and since the diagnostic accuracy of the Glucagon test is the same of that of resting plasma catecholamines, the former does not appear to offer additional advantages in the diagnosis of incidentally discovered pheochromocytomas.

17-hydroxyprogesterone response to ACTH in bilateral and monolateral adrenal incidentalomas

The aim of our study was to assess the frequency of 21-hydroxylase deficiency, a cause of congenital adrenal hyperplasia (CAH), in incidentally discovered asymptomatic adrenal masses (incidentalomas) and to compare the prevalence of this enzymatic disorder in monolateral (M) and bilateral (B) forms. Twenty-seven patients with incidentalomas (12 M and 15 B) and 16 sex and age-matched controls (C) received synthetic adrenocorticotropin (ACTH, 250 μg iv). Plasma 17-OHprogesterone (17-OHP) and Cortisol were collected in basal conditions and after 30, 60, 90 minutes. Basal plasma 17-OHP in C [1.25±0.15 (0.61) ng/ml, mean±SE (SD)] was not significantly different from that in patients with M [0.85±0.13 (0.44) ng/ml] or B [0.94±0.23 (0.90) ng/ml] incidentalomas. After ACTH, 17-OHP levels significantly (p<0.05) increased in C, in M and B incidentalomas. However, the rise in plasma 17-OHP in C both in terms of peak [2.5±0.28 (1.1) ng/ml] and of AUC values [174+16 (64) ng/ml/min] was significantly lower than that observed in M [peak 6.32±1.66 (5.7) ng/ml, p<0.01; AUC 410±111 (385.5) ng/ml/min, p<0.01] and in B [peak 8.84±1.98 (7.65) ng/ml, p<0.001; AUC 613±149 (579.3), ng/ml/min, p<0.001] incidentalomas. Individual data indicated that while 17-OHP response to ACTH in C never reached 5 ng/ml (cut-off for normal response), 16 out of 27 patients with incidentalomas (59.2%) exceeded this value. Moreover, the abnormal response was more frequently observed in B (66.6%) than in M (50%) incidentalomas. Basal and stimulated plasma Cortisol did not differ among the three groups. In conclusion, our data indicate that in adrenal incidentalomas the endocrine pattern of 21-hydroxylase deficiency is very common and that this enzymatic defect is more frequent in bilateral than in monolateral lesions.

Utility of plasma dehydroepiandrosterone sulphate determination in adrenal incidentalomas

To evaluate whether low DHEA-S levels are predictors of cortical origin, benignity and hormonal activity in incidentally detected adrenal masses, thirty-five patients with adrenal incidentalomas were studied. All patients were operated on and the diagnosis was histologically confirmed. Basal endocrine workup included plasma determination of cortisol before and after dexamethasone (1 mg overnight), plasma ACTH (08:00 h), 17-OH-progesterone, testosterone and potassium, standing plasma renin activity and aldosterone, supine and standing plasma noradrenaline and adrenaline. If necessary, we performed dexamethasone suppression tests at low (2 mg) and high (8 mg) doses, or the loperamide test (16 mg os) for evaluation of glucocorticoid activity and the glucagon test (1 mg iv) for exploring adrenal medulla function. Plasma DHEA-S was measured in all patients and the results were compared to those obtained in controls matched for age, sex and menopausal status. Suppression of DHEA-S was found in 11 out of 35 patients (31.5%). However, this hormonal finding occurred in 50% of the extracortical adrenal lesions, while in proven cortical adenomas (no.=19) it was detected in only 5 patients (26.3%). Sensitivity, specificity, diagnostic accuracy and positive predictive value of low DHEA-S in indicating a cortical origin of the mass were 0.27, 0.0, 0.25, and 0.80. In malignancies (no.=6) low DHEA-S levels were found in 1 out of 2 metastases and never in cortical carcinomas. Sensitivity, specificity, diagnostic accuracy and positive predictive value of low DHEA-S in indicating a benign form were 0.34, 0.83, 0.42, and 0.91. Six out of 19 patients with cortical adenomas showed signs of hypothalamic-pituitary adrenal (HPA)-axis dysfunction. Low DHEA-S levels were found in 50% of adenomas with HPA-axis abnormality and in 15.3% of adenomas without hormonal activity. Sensitivity, specificity, diagnostic accuracy, and positive predictive value of low DHEA-S levels in indicating hormonal activity of the mass were 0.50, 0.84, 0.73, and 0.60. Our data indicate that the association between low DHEA-S levels and adrenal incidentalomas is frequent. Low DHEA-S appears to be a poor predictor of hormonal activity with low sensitivity and specificity in respect of cortical origin and benignity of the mass. In conclusion, our results show that DHEA-S measurement does not offer relevant clinical information in the management of adrenal incidentalomas.

Effects of long-term simvastatin treatment on testicular and adrenal steroidogenesis in hypercholesterolemic patients

Simvastatin is an inhibitor of 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase, the key enzyme in the synthesis of cholesterol, recently introduced in the therapy of hypercholesterolemic patients. Cholesterol is the precursor of the biosynthesis of steroid hormones; thus, a reduction of the availability of cholesterol in the adrenal and testicular cells may reduce the synthesis of corticosteroids and androgens. To establish whether chronic therapy with simvastatin interferes with the integrity of the hypothalamic-pituitary-adrenal axis and with the adrenal and testicular reserve, we administered simvastatin orally in a single-day 10 mg dose for 6 months in 8 mildly hypercholesterolemic male patients. At weeks 0, 6 and 24 of treatment we evaluated the lipids, the activity of the hypothalamic-pituitary-adrenal axis by means of the Corticotropin-Releasing Hormone (CRH) test, the adrenal reserve by means of the Corticotropin rapid test and, finally, the testicular reserve by means of the Human Chorionic Gonadotropin (HCG) test. Total cholesterol and LDL-cholesterol were significantly reduced by Simvastatin, while the HDL-cholesterol and triglycerides did not change significantly. The hormonal responses to CRH, ACTH and HCG tests at weeks 6 and 24 of treatment were comparable to those obtained in basal conditions. We conclude that Simvastatin, while effective in reducing total and LDL-cholesterol in hypercholesterolemic male patients, did not interfere with hypothalamic-pituitary-adrenal axis activity or with basal and stimulated adrenal and testicular steroidogenesis.

Serotoninergic receptor activation by dextrofenfluramine enhances the blunted pituitary-adrenal responsiveness to corticotropin-releasing hormone in obese subjects

To explore the interrelationships between the serotoninergic system and the hypothalamic-pituitary-adrenal (HPA) axis in human obesity, we evaluated cortisol and adrenocorticotropic hormone (ACTH) response to synthetic human corticotropin-releasing hormone (hCRH, 1 microgram/kg intravenously [IV]) before and after stimulation of the serotoninergic system by dextrofenfluramine (d-FF, 30 mg/d for 3 months) in nine obese women. These responses were compared with a CRH test (1 microgram/kg) carried out in nine age-matched normal-weight women. Plasma cortisol of obese subjects did not significantly increase after CRH (peak value 127.1 +/- 11.2 ng/mL v 104.1 +/- 9.5 ng/mL). This response was lower (P less than .005) than in the controls, in whom the basal cortisol value of 120.6 +/- 11.8 ng/mL reached a peak value of 221.2 +/- 13.4 ng/mL. However, after administration of d-FF, CRH significantly increased (P less than .0001) plasma cortisol (peak value 170.6 +/- 18.0 ng/mL v 111.5 +/- 10.8 ng/mL) and the response was enhanced (P less than .05) as compared with that obtained before d-FF. The ACTH levels of our patients showed a small increment after CRH injection (peak value 13.5 +/- 1.7 pg/mL v 9.6 +/- 1.1 pg/mL), but the hormonal response was lower (P less than .005) than in controls (peak value 38.1 +/- 5.5 pg/mL v 13.8 +/- 0.8 pg/mL). However, after d-FF, CRH induced a significant increment (P less than .05) in plasma ACTH at 30 minutes (20.4 +/- 3.7 pg/mL v 10.9 +/- 0.9 pg/mL) and 45 minutes (18.0 +/- 2.6 pg/mL), even though this response was not significantly different from that observed before d-FF administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Blunted growth hormone (GH) responsiveness to GH-releasing hormone in obese patients: Influence of prolonged administration of the serotoninergic drug fenfluramine

The aim of the present study was to ascertain if reduced central serotoninergic activity might contribute to the well-known blunted growth hormone (GH) response to GH-releasing hormone (GHRH) in obese patients. Thus, we studied the effect of prolonged stimulation of the serotoninergic system by fenfluramine (FF; 60 mg twice daily for 7 days) on GHRH-induced GH release in nine obese and seven normal subjects. In controls, GHRH (100 micrograms intravenously [IV]) injection increased GH levels from 2.3 +/- 1.8 (+/- SE) to 18.5 +/- 2.8 mU/L, P less than .002. FF administration enhanced both basal and GHRH-stimulated GH levels (peak, 38.4 +/- 8.3 v 6.9 +/- 2.6 mU/L, P less than .002). This response was significantly higher (P less than .02) than in pretreatment. In obese patients, GH responsiveness to GHRH was slight (peak, 7.1 +/- 2.0 v 0.6 +/- 0.18 mU/L, P less than .01) and lower (P less than .01) than in controls. FF administration did not affect this response. In controls, the enhanced FF-induced GH release after a maximal dose of GHRH indicates that serotoninergic activation influences GH secretion and that the mechanism involved is independent of endogenous GHRH. In obese patients, we found a blunted GH responsiveness to GHRH that was not affected by FF, thus supporting the hypothesis that the serotoninergic control on GH release is impaired.

Effect of fenfluramine on prolactin and thyroid-stimulating-hormone response to thyrotropin-releasing-hormone in obese and normal women

SummaryIn order to demonstrate the suggested failure of the serotoninergic system in human obesity and to evaluate the role of central serotoninergic activity in prolactin (PRL) and thyroid stimulating hormone (TSH) release in this condition, 13 euthyroid obese and 9 healthy women of normal weight were studied. A TRH test (200 µg i. v.) was performed before and after administration of fenfluramine (FF) 60 mg b. d. for 14 days. In the controls, FF did not modify the expected significant increase in PRL induced by TRH. In obese patients, however, the PRL levels was significantly increased after TRH, but the increase was less than in the controls. After FK the PRL response to TRH was larger than in the pretreatment phase, with values similar to those observed in normal subjects. In neither group FF did change the TSH-stimulating effect of TRH, but the hormonal response in obese patients was greater than in the controls.The restoration of the responsiveness of PRL to TRH after central serotoninergic stimulation confirms the hypothesis that a failure of the serotoninergic system may occur in human obesity. Since FF does not interfere with the secretory pattern of basal and stimulated TSH in normal or obese subjects, the serotoninergic system does not seem to play a major role in the control of TSH secretion.

Naloxone does not modify fenfluramine-induced prolactin increase in obese patients.

objective To evaluate whether the supposed physiological interaction between serotoninergic and opioidergic pathways in the modulation of PRL release is preserved in human obesity, a pathological condition in which these two systems are greatly impaired

Possible mechanism of prolactin unresponsiveness to repeated sulpiride administration in man

SummaryThe mechanisms of prolactin (PRL) unresponsiveness to repeated sulpiride (SUL) injections were investigated in 7 normal males. The experimental protocol consisted of two phases, separated by a 5 day interval. In both phases the administration of 1 mg/kg i. m. of SUL was followed 24 hours later, by the administration of the same dose of SUL together with either placebo (PL, 2 ml saline i. v.) or TRH (200 mcg i. v.). A control TRH test (200 mcg i. v.) was also performed. PRL showed a significant increase after the administration of SUL alone in both phases. Twenty-four hours later plasma PRL was still higher than the basal level and it was not significantly modified by administration of SUL+PL, or by SUL+TRH. The data seem to show that the lack of responsiveness of PRL to repeated administration of SUL is not due to refractoriness of dopaminergic receptors but probably to exhaustion of the hypophyseal PRL pool.