F. Cavagnini

Diagnosis and treatment of acromegaly complications

The Pituitary Society in conjunction with the European Neuroendocrine Association held a consensus workshop to develop guidelines for diagnosis and treatment of the co-morbid complications of acromegaly. Fifty nine pituitary specialists (endocrinologists, neurosurgeons and cardiologists) assessed the current published literature on acromegaly complications in light of recent advances in maintaining tight therapeutic control of GH hypersecretion. The impact of elevated GH levels on cardiovascular disease, hypertension, diabetes, sleep apnea, colon polyps, bone disease, reproductive disorders, and neuropsychologic complications were considered. Guidelines are proposed for effective management of these complications in the context of overall acromegaly control. When appropriate, requirements for prospective evidence-based studies and surveillance database development are enunciated. Effective management of co-morbid acromegaly complications will lead to improved morbidity and mortality in acromegaly.

Effects of gamma aminobutyric acid (GABA) and muscimol on endocrine pancreatic function in man

The high concentrations of gamma aminobutyric acid (GABA) in the pancreatic islets and the neurotransmitter role played by this amino acid in the central nervous system, make it plausible that GABA also intervenes in the control of endocrine pancreatic function. In 12 normal subjects, a single oral dose of 5 or 10 g GABA, as compared to placebo, caused a significant (p less than 0.01) and dose-dependent (p less than 0.01) increase of plasma levels of immunoreactive insulin, C peptide and glucagon, without affecting plasma glucose concentration. By contrast, in 15 additional subjects, a single oral dose of 5 mg muscimol, a specific GABA receptor agonist, did not consistently influence the above parameters. Although the lack of effects of muscimol might indicate that the action of GABA is not mediated through specific receptors, the results with GABA suggest that this amino acid plays a specific role in the regulation of endocrine pancreatic function.

Somatostatin analogs and gallstones: a retrospective survey on a large series of acromegalic patients

Context: Development of gallstones (GS) is reported during the use of somatostatin analogs (SA) that are at present the mainstay for the medical treatment of acromegaly. Objective: To review the prevalence and clinical and biochemical correlates of GS in acromegalic patients. Design and seting: Retrospective survey on hospital records in acromegalic patients followed up in the last 20 yr in tertiary referral centers. Patients: Four hundred and fifty-nine patients (272 females). Main outcome measures: According to SA use and GS occurrence, patients were divided in 4 groups: 1) treated with SA without GS (SA+GS−), 2) GS developed while on SA (SA+GS+), 3) GS without SA use (SA−GS+), 4) neither GS nor SA (SA−GS−). Results: Patients were unevenly distributed in the 4 groups: 232, 125, 38, 64, respectively, pointing to a prevalence of GS in acromegaly of 8.3% at diagnosis with an additional 35% developing GS during SA. GS occurred after 3 months-18 yr (median 3 yr) of SA treatment, were diagnosed after symptoms in 17.6%, were associated to steatosis, ultrasound biliary dilation, and biochemical cholestasis, in 25.6%, 12.8%, and 4% of patients, respectively. Ursodehoxicolic acid was administered after GS occurrence, causing their dissolution in 39% of patients after 3–48 months (median 12). Cholecystectomy was performed in 16.8% of patients in group 2. At multivariate analysis obesity, dyslipidemia, and SA treatment were independent predictors of GS onset, whereas gender and age were not. Conclusions: GS are a frequent occurrence in acromegalic patients treated with SA, may occur at any time, but are seldom symptomatic or prompt acute surgery. Obesity and dyslipidemia appear to play a major role in the occurrence of GS in acromegalic patients on SA treatment.

Treatment of Cushing's syndrome with the long-acting somatostatin analogue SMS 201-995 (Sandostatin)

Three patients with Cushings disease and one patient with paraneoplastic hypercortisolism were treated for 24‐49 days with the long‐acting analogue of somatostatin, SMS 201‐995, Sandoz (SMS), administered in increasing doses up to 400‐1200 μg daily. In the three Cushings patients during SMS treatment plasma ACTH displayed an initial rise and a subsequent decrease. The pattern of urinary free cortisol (UFC) tended to be opposite to that of ACTH. In one of these patients, UFC continued to decrease throughout the treatment, without becoming normal. In the patient with paraneoplastic hypercortisolism, SMS was associated with a progressive decrease, though not the normalization, of UFC and of ACTH and cortisol levels. The reciprocal changes of the ACTH and UFC levels observed in the three Cushings patients receiving SMS suggest that the peptide may act temporarily by inhibiting glucocorticoid secretion. In view of the marked reduction of UFC recorded in 1 of the 3 Cushings patients and in the patient with paraneoplastic Cushings syndrome, administration of SMS seems worth trying in cases of ACTH‐dependent hypercortisolism requiring medical treatment.

Increased prevalence of prolonged QT interval in males with primary or secondary hypogonadism: a pilot study.

Symptoms and signs of male hypogonadism span all organ systems, including the cardiovascular apparatus. The electrocardiographic QT interval reflects cardiac ventricular repolarization and, if prolonged, increases the risk of malignant arrhythmias. QT interval duration is similar in boys and girls during childhood, but shortens in males after puberty and experimental studies suggest that testosterone is a major contributor to shortening of QT interval in men. The aim of the present pilot study was to assess the duration of ventricular repolarization in adult males with primary or secondary hypogonadism. Standard ECG recordings were performed in 26 men (mean age 39.2 +/- 2.17 years) with pituitary or testicular hypogonadism and repeated in 15 patients during testosterone replacement. Twenty-six age-matched control men were also analysed. Measured QT intervals were corrected for heart rate according to Bazzetts formula (QTc = QT/radical RR interval). The prevalence of prolonged QTc was considerably higher in hypogonadal patients (four of 26 men) than in control men (none, p < 0.05) and in the general, healthy population (<2.5%). QTc interval normalized on hormone replacement therapy in the four patients presenting prolonged QTc in the hypogonadal state. Heart rate and left ventricular mass did not differ among the two groups and no known QT-prolonging factor was apparent in patients with abnormal QTc interval. In conclusion, a high number prolonged QT interval measurements was observed in hypogonadal men who may therefore be at increased risk for cardiac arrhythmias. This observation reveals an additional feature of male hypogonadism, which may benefit from testosterone replacement therapy.

Effects of acetylsalicylic acid and indomethacin on growth hormone secretion in man

To investigate the possibility that prostaglandins (PG) take part in the control of growth hormone (GH) secretion in humans, we have studied the effects of protracted and acute administration of acetylsalicylic acid (ASA) and indomethacin (ID), two PG synthesis inhibitors, on basal and insulin-stimulated GH secretion in normal volunteers. In eight subjects, oral administration of 3-2 g daily of ASA for 4 days clearly reached GH response to insulin hypoglycemia (p less than 0.01, ANOVA). In six additional subjects, GH response to hypoglycemia was not modified by a 4-day oral treatment with 300 mg daily of ID. The pattern of plasma free fatty acids (FFA) and blood glucose during the insulin tolerance test was not significantly affected by ASA treatment. After ID the O time value of the above parameters was somewhat higher than under basal conditions, while the drop of blood glucose, but not to FFA, was slightly more pronounced. Acute oral administration of 1.5 g ASA in 12 subjects did not appreciably modify baseline plasma GH, FFA, and blood glucose levels. By contrast, a single oral dose of 100 mg ID in 12 subjects caused a moderate but significant rise (p less than 0.05) of plasma GH levels together with a clear elevation (p less than 0.01) of plasma FFA and blood glucose levels with respect to a group of controls treated with a placebo. Collectively these results are compatible with the possibility that PG play a physiologic stimulating role in the control of GH secretion, although an effect of ASA and ID unrelated to PG inhibition cannot be ruled out, In any event, in view of the number of endocrine and metabolic alterations induced by ASA and ID, these drugs seem to merit further study.

Ghrelin Stimulates Adrenocorticotrophic Hormone (ACTH) Secretion by Human ACTH‐Secreting Pituitary Adenomas In Vitro

Ghrelin is a brain‐gut peptide with wide‐ranging endocrine, metabolic, cardiovascular and neural effects. Ghrelin, like its synthetic counterparts, the growth hormone (GH) secretagogues, has been shown to markedly stimulate adrenocorticotrophic hormone (ACTH) and cortisol secretion in humans and the ACTH‐releasing effect of GH secretagogues is even greater in patients with pituitary ACTH‐secreting tumours. Furthermore, these tumours synthesize ghrelin itself, suggesting an intrapituitary ghrelin circuit. The aim of the present study was to evaluate the effect of ghrelin on ACTH secretion by human pituitary corticotroph tumours in vitro to test the functionality of this circuit. Nine ACTH‐secreting pituitary tumours (four microadenomas, five macroadenomas) were collected during surgery and incubated with 10–100 nM human ghrelin or with 10 nM human corticotrophin‐releasing hormone (CRH). Control experiments were performed in rat anterior pituitary primary cultures. ACTH secretion was assessed after 4 h and 24 h incubation by immunometric assay. After 4 h of incubation with ghrelin, medium ACTH concentrations were two‐ to ten‐fold higher compared to ACTH concentrations in unstimulated wells. The ACTH‐releasing effect of ghrelin was significantly less than the response elicited by 10 nM CRH (up to 40‐fold) Similar results were obtained after 24 h of incubation and a superimposable response pattern was observed in rat anterior pituitary primary cultures. The present study demonstrates that the endogenous GH secretagogue, ghrelin, stimulates ACTH secretion directly from human tumoural corticotrophs, as well as from normal rat pituitary, and indicates that the marked ACTH release elicited by ghrelin in patients with Cushings disease in vivo is due, at least in part, to its action on the pituitary tumour. However, the reversal of the response pattern reported in vivo, with ghrelin proving a lesser stimulant than CRH in vitro, suggests that additional, suprapituitary mechanisms are involved in the in vivo response. Moreover, these data uphold the concept of a functional intratumoural ghrelin paracrine circuit in human corticotroph adenomas.

Tissue-specific dysregulation of 11β-hydroxysteroid dehydrogenase type 1 and pathogenesis of the metabolic syndrome

Glucocorticoids are important regulators of glucose, lipid and protein metabolism, acting mainly in the liver, adipose tissue and muscle. Chronic glucocorticoid excess is associated with clinical features, such as insulin resistance, visceral obesity, hypertension, and dyslipidemia, which also represent the classical hallmarks of the metabolic syndrome. Elevenß-hydroxysteroid dehydrogenase type 1 (11ß-HSD-1), a key intracellular enzyme which catalyses the conversion of inactive cortisone to active cortisol, has been implicated in the development of the metabolic syndrome. The shift of this reaction towards cortisol generation may lead to tissutal overexposure to glucocorticoids even with normal circulating cortisol levels. The most robust evidence in support of a pathogenetic role of this enzyme in the development of the metabolic syndrome has been reported in experimental animals, whereas results of human studies are less convincing with several case control and cross-sectional studies showing an association between with 11ß-HSD-1 setpoint and individual features of the metabolic syndrome. However, recent data suggest a tissue-specific rather than systemic alteration of this shuttle, with down-regulation in liver but up-regulation in adipose tissue and skeletal muscle of obese subjects. New techniques based on direct tissutal estimates of cortisol/cortisone ratios are clearly needed to precisely assess the role of enzyme in all target tissues. If confirmed, these results would prompt the development of selective and tissuespecific 11ß-HSD-1 inhibitors to decrease insulin resistance and treat the metabolic syndrome, thus contrasting the harmful effects of glucocorticoid excess in peripheral tissues

Evaluation of hypothalamic-pituitary function in patients with thalassemia major

The increased survival of patients with thalassemia major, made possible by more adequate therapeutic regimens, has emphasized the importance of the endocrine abnormalities often associated with this disease. In twelve thalassemic patients, we evaluated the hypothalamic- pituitary function by measuring plasma levels of anterior pituitary hormones under basal conditions and in the course of provocative tests. An impairment of growth hormone (GH) secretion was demonstrated in a considerable proportion (7/12) of these patients. In some of them failure of GH response to insulin-hypoglycemia and normal hormone rise after growth hormone-releasing hormone indicate a hypothalamic defect. A defective prolactin secretion was observed in the female hypogonadic but not in the male thalassemic patients. This abnormality appears to be dependent on estrogen deficiency rather than on a hypothalamic-pituitary dysfunction. In our series a high prevalence (8/12) of hypogonadism was also noticed. In these cases, the low gonadotropin levels and their unresponsiveness to gonadotropin-releasing hormone are compatible with a hypothalamic and/or pituitary damage. Lastly, the enhanced ACTH responses to the stimuli associated to a reduced Cortisol release suggest the existence, in these patients, of a diminished adrenocortical reserve. On the whole, this study has shown several derangements of the hypothalamic-pituitary function in thalassemia. This emphasizes the need for careful endocrine surveillance in this disease.

Increased lipid peroxidation in adult GH-deficient patients: Effects of short-term GH administration

Objective: Adult GH deficiency (GHD) syndrome is characterized by increased risk of atherosclerosis and hence of cardio- and cerebrovascular mortality. Oxidative stress appears to play an important role in early atherogenesis. Oxidized LDL represents an important predictor of cardiovascular risk and is mainly responsible for oxidative damage of the endothelium. Its concentrations are increased in GHD, but the association between this abnormality and oxidative stress is still unclear, due to the discordant results yielded by the few available studies. Design and methods: In 13 GHD patients, plasma lipid peroxide concentrations were measured before and after a 4-month treatment with recombinant human GH (rhGH) and compared with those of 13 age-and sex-matched controls. In the same subjects, the so-called “lag-time”, an index of anti-oxidant activity and thus of plasma oxidative balance, was also measured using a fluorescence kinetics method. Results: Before treatment, peroxide levels were significantly higher in patients than in controls (374.0±31.52 vs 268.0±8.51 U.C., p<0.01), whereas the lag-time was significantly lower (113.0±10.70 vs 168.0±7.80 min, p<0.01). RhGH administration to patients resulted both in a significant decrease in lipid peroxide levels (from 374.0±31.52 to 336.0±33.17 U.C., p<0.01) and a significant prolongation of lag-time (from 113.0±10.70 to 144.0±15.00 min, p<0.01). After treatment, both parameters were no longer significantly different in patients and controls. Lagtime and peroxide levels at baseline did not show any correlation with IGF-I concentrations in GHD patients. After replacement therapy, however, lag-time was positively (r2= 0.62, p<0.01), and peroxide levels negatively (r2=0.41, p<0.05), correlated with IGF-I levels. Conclusions: These data support the view that adult GHD syndrome is characterized by an unbalance between pro- and anti-oxidant factors with marked preponderance of the former. This abnormality, likely contributing to the increased atherogenic risk of GHD patients, is corrected by short-term GH administration at a dose able to increase, although not to fully normalize, IGF-I levels.