Acromegaly

Acromegaly and associated tumours: what should gastroenterologists know?

Acromegaly is a clinical syndrome caused by the excessive production of growth hormone. It is associated with high morbidity and significantly increased mortality, mainly due to cardiovascular and respiratory complications, and cancer. Mortality is reduced to that of the general population following successful treatment, in other words, when insulin-like growth factor (IGF-I) and growth hormone values return to normal levels. Not all tumours associated with this syndrome benefit from cost-effective early diagnosis programmes. An in-depth knowledge on the part of clinicians of the morbidity and mortality associated with acromegaly, allowing them in many cases to anticipate the expected clinical course of the disease, is the best therapeutic and follow-up strategy in these patients.

Is every joint symptom related to acromegaly?

Acromegaly is a chronic endocrinopathy characterized by the hypersecretion of growth hormone and insulin-like growth factor-1. Musculoskeletal pain is a frequent problem encountered in acromegaly and is associated with a reduction in the quality of life. In this study, the presence of inflammatory and degenerative rheumatologic diseases in acromegaly has been retrospectively evaluated. Forty patients with acromegaly who were in remission according to laboratory findings, but still having joint and back pain problems, were referred to rheumatology outpatient clinic and all the patients were examined by clinical, radiological, and laboratory data. Mean age was 47.1 years (22-75). When the radiological data were evaluated, erosions of the left sacroiliac joint were found by means of magnetic resonance imaging in 1 patient and degenerative joint changes were observed in 24 patients by X-ray imaging. However, there was no pathology in the radiological data of 15 patients. Laboratory data revealed antinuclear antibody positivity (3 nucleolar and 1 homogeneous) in 4 patients, rheumatoid factor positivity in 4, and cyclic citrullinated peptide positivity only in 1 patient. The diagnosis of an inflammatory rheumatologic disease, including rheumatoid arthritis, ankylosing spondylitis, or undifferentiated connective tissue disease was made in 3 patients. Besides, the diagnosis of diffuse idiopathic skeletal hyperostosis was also established in 6 patients. While degenerative joint diseases were frequently observed in our group similar to the literature, inflammatory rheumatologic diseases were also found in three patients. Distinguishing these two diseases is important because response to medical treatment is dramatically better in inflammatory diseases than in degenerative pathologies. A multidisciplinary approach is imperative for appropriate management of these patients.

Secondary diabetes associated with principal endocrinopathies: the impact of new treatment modalities

The secondary occurrence of type 2 diabetes with various hormonal diseases (e.g. pituitary, adrenal and/or thyroid diseases) is a recurrent observation. Indeed, impaired glucose tolerance (IGT) and overt diabetes mellitus are frequently associated with acromegaly and hypercortisolism (Cushing syndrome). The increased cardiovascular morbidity and mortality associated with acromegaly and Cushing syndrome may partly be a consequence of increased insulin resistance that normally accompanies hormone excess. Acromegalic patients are insulin resistant, both in the liver and in the periphery, displaying hyperinsulinemia and increased glucose turnover in the basal post-absorptive states. The prevalence of diabetes mellitus and that of IGT in acromegaly is reported to range 16-56%, whereas the degree of glucose tolerance seems correlated with circulating growth hormone (GH) levels, age, and disease duration. Moreover, a family history of diabetes and concomitant presence of arterial hypertension have been found to predispose to diabetes as well. GH has physiological effects on glucose metabolism, stimulating gluconeogenesis and lipolysis, which results in increased blood glucose and free fatty acid levels. Conversely, insulin-like growth factor 1 (IGF-I) enhances insulin sensitivity primarily on skeletal muscles. However, in acromegaly, increased IGF-I levels are unable to counteract the insulin-resistance status determined by GH excess. Therapy with somatostatin analogues (SSAs) induce control of GH and IGF-I excess in the majority of patients, but their inhibitory effect on pancreatic insulin secretion might complicate the overall effect of this treatment on glucose tolerance. Hypercortisolism produces visceral obesity, insulin resistance, and dyslipidemia that together with hypertension, hypercoagulability, and ventricular morphologic and functional abnormalities increase cardiovascular risk, and persist up to 5 years after resolution of hypercortisolism. Hypercortisolism leads to hyperglycaemia and reduced glucose tolerance, determines insulin resistance, stimulates hepatic gluconeogenesis and glicogenolisis. In Cushing syndrome the prevalence of diabetes varies between 20 and 50%, but probably this prevalence is underestimated, as not always an oral glucose tolerance test is performed in the presence of an apparently normal fasting glycaemia. Again, disease duration, rather than hormone levels, seems to be the major determinant in the occurrence of systemic complications in Cushing syndrome. Due to the impact they have on mortality and morbidity in both acromegaly and Cushing syndrome, these complications should be treated aggressively. In patients with neuroendocrine tumours (NETs) the occurrence of altered glucose tolerance may be due to a decreased insulin secretion, like it happens in patients who underwent pancreatic surgery and in those with pheochromocytoma, or to an altered counterbalance between hormones, such as in patients with glucagonoma and somatostatinoma. Moreover, SSAs represent a valid therapeutic choice in the symptomatic treatment of NETs, and also in this case the medical therapy of the primary disease, may have a significant impact on the prevalence of glucose metabolism imbalance. In thyroid disorders, an abnormal glucose tolerance may be principally encountered in hyperthyroidism. The pathogenesis is complex and scant data on prevalence and severity are found in the literature. Adequate treatment for glucose imbalance is mandatory in these peculiar patients in line with the American Diabetes Association and the European Association for the Study of Diabetes consensus statement. In particular, since traditional insulins have two features that may complicate therapy (absorption profiles, delayed onset of action and peak activity), the new insulin analogues could be of particular interest in the management of the secondary diabetes associated with endocrinopathies, considering the frailty of these patients. Indeed, it has been demonstrated that insulin glargine, given once daily, reduces the risk of hypoglycaemia compared with other formulations, and can facilitate a more aggressive insulin treatment in this class of patients.

Current pharmacotherapy for acromegaly: a review

Acromegaly is associated with considerable morbidity and excess mortality; however, after effective treatment, both morbidity and mortality risks improve. Growth hormone excess in acromegaly can be controlled in many patients by pharmacotherapy alone, and with a combination of transsphenoidal surgery and pharmacotherapy in almost all patients. Since the clinical introduction of pegvisomant, a growth hormone-receptor antagonist, the role of radiotherapy is restricted. This review focuses on the treatment options for acromegaly (e.g., surgery, radiotherapy and pharmacotherapy with the depot preparations of the somatostatin analogues octreotide long-acting release formulation, lanreotide slow-release formulation and lanreotide Autogel, the growth hormone antagonist pegvisomant and the dopamine agonist cabergoline). Pharmacological characteristics of these drugs and the clinical and adverse effects are discussed individually and in relation to the other treatment modalities. The evidence for biochemical goals aimed at during medical treatment and the costs of pharmacotherapy are discussed. A new treatment algorithm is proposed, in which the choice between primary medical treatment and primary surgery is individualised, dependent on adenoma size and extension, patient factors (age, preference for therapy, contraindication for surgery), surgical experience of the centre and octreotide sensitivity of the adenoma. The high cost of lifelong medical treatment, especially of pegvisomant, must be weighed against the cost of a single surgical procedure.

Treatment strategies for acromegaly

Acromegaly is a chronic debilitating disorder caused by a growth hormone (GH)-producing pituitary adenoma. Active acromegaly is associated with a two- to fourfold increased mortality risk, mainly from cardiovascular disease. Transsphenoidal surgery is considered as the treatment of choice because of the rapidity of cure and normalisation of survival. Secondary treatment modalities are radiotherapy and medical treatment, and are important because surgery in the best hands cures only approximately 60% in long-term studies. Medical treatment with slow-release formulations of somatostatin are now widely used, also as primary treatment, and appear to be safe and effective in 50-60% of the patients. However, no data on mortality risk with these drugs is available. Recently, a GH-receptor blocking agent, pegvisomant, was licensed for use in acromegaly and appears to normalise IGF-1 in almost all patients. This article examines the pathophysiology of acromegaly, currently used medicines and their safety and efficacy, and the new drugs that are in development.

Octreotide long-acting release (LAR): a review of its use in the management of acromegaly

Octreotide long-acting release (LAR) is a somatostatin analogue designed for once monthly intramuscular injection. As with endogenous somatostatin, octreotide LAR inhibits secretion of growth hormone (GH) as well as various other peptide hormones. In the treatment of acromegaly, octreotide LAR effectively controlled the secretion of GH and insulin-like growth factor-1 (IGF-1) in about 55-70% of patients (n > 100) who had previously been treated with somatostatin analogues, a similar degree of control to that observed with subcutaneous octreotide and lanreotide slow release (SR). Progressive control of serum levels of GH and IGF-1 was achieved with octreotide LAR in clinical studies of up to 4 years' duration. In addition, primary therapy with octreotide LAR provided effective control of GH and IGF-1 secretion, particularly in patients with a pretreatment GH level <20 microg/L. The percentage of patients achieving a target serum GH level of <2-2.5 micro g/L or normal IGF-1 levels was significantly greater with octreotide LAR 10, 20 or 30 mg every 28 days than with lanreotide SR 30 mg every 7-14 days in a large (n = 125) sequential, 6-month study, but was not significantly different between treatment groups in a small, randomised, nonblind, parallel group study of previously untreated patients. The volume of pituitary tumour shrinkage achieved with octreotide LAR or lanreotide SR was also similar ( approximate, equals 33% after 24 months). Acromegaly symptoms, such as headache, increased perspiration, paraesthesia, fatigue and osteoarthralgia were improved during treatment with octreotide LAR or lanreotide SR. Overall, octreotide LAR is generally well tolerated by most patients. The incidence of gastrointestinal symptoms is about 30% but, in most cases, events are transient and mild to moderate. Gallbladder abnormalities (sediment, sludge, microlithiasis and gallstones) can occur, but only 1% have become symptomatic to date. The prevalence of biliary abnormalities did not change after switching from subcutaneous octreotide, or from lanreotide SR, to octreotide LAR. Glucose metabolism can be affected by octreotide LAR in some patients; about 15% become hyperglycaemic, usually mild in severity. In summary, octreotide LAR controls GH and IGF-1 secretion in about 55-70% of patients with acromegaly. Octreotide LAR is administered intramuscularly every 28 days, offering improved patient compliance and convenience over three-times-daily subcutaneous octreotide. Long-term therapy provides progressive control of serum GH and IGF-1 levels, and is generally well tolerated by most patients. Thus, for the medical management of acromegaly, octreotide LAR is an effective, well tolerated and convenient treatment option.

Pituitary tumor endocrinopathies and their endocrine evaluation

Pituitary tumors, depending on their respective cell type, manifest various endocrinopathies. Prolactinomas may present as hypogonadism and galactorrhea and can be diagnosed by measuring morning prolactin levels. Gonadotropinomas rarely cause gonadal hyperstimulation, and dynamic thyrotropin-releasing hormone stimulation testing is often required to elicit a diagnostic gonadotropin and/or subunit secretory response. Acromegaly is a multisystemic debilitating disease for which early diagnosis and treatment are crucial. Diagnostic criteria include a lack of plasma growth hormone suppression during the oral glucose tolerance test and elevation of age- and sex-matched insulin growth factor-1 levels. Patients harboring corticotropin-secreting adenomas characheristically present with signs and symptoms of hypercortisolism. Inferior petrosal sinus sampling for corticotropin may be required for microadenoma localization. Thyrotropinomas produce inappropriate thyrotropin (TSH) secretion and hyperthyroidism. The new third-generation TSH assay has improved the rate of detection of these lesions at an earlier stage.

Gingival enlargement in acromegaly

In this study, we investigated gingival enlargement in patients with acromegaly as a component of the disease. Eleven patients (5 males, 6 females) were evaluated. Diagnosis was confirmed with typical clinical features and laboratory. Oral examinations were carried out by the same periodontist. During the examination, plaque index, gingival index, probing pocket depths, and gingival enlargement values were evaluated. Duration of the disease was between 0.2 and 13 yr. Seven patients had pituitary macroadenomas and four had microadenomas during their initial diagnosis. Only one patient was newly diagnosed. The other patients had previously undergone surgery. Gingival enlargement was found in eight patients. Seven patients with gingival enlargement also had prognathism, and one patient had prognathism associated with gingival enlargement. These findings demonstrate that acromegaly that results in overgrowth in various organs should be considered one of the causes of gingival enlargement.

Acromegaly: a new therapy

BACKGROUND

The treatment of acromegaly can be challenging. Despite a multimodality approach (surgery,radiation, dopamine agonists, somatostatin analogs), many patients do not achieve normalization of serum insulin-like growth factor I (IGF-I) concentrations.

METHODS

The author discusses the characteristics and indications of pegvisomant therapy for patients with acromegaly and compares the use of this newly developed GH receptor antagonist with other pharmacological agents such as somatostatin and dopamine agonists.

RESULTS

Therapy with pegvisomant allows serum IGF-I concentrations to be normalized in up to 97% of patients with acromegaly, including those who have failed other treatment modalities. With this agent,circulating GH levels increase as a result of the drop in IGF-I levels. The rise is rapid (within 2 weeks) and does not appear to be progressive over time.

CONCLUSIONS

Published studies have shown pegvisomant to have efficacy in the treatment of acromegaly. As it appears to be well tolerated and safe, this novel compound may be an important therapeutic option for patients with acromegaly. Additional study of this novel agent and its mode of action is warranted.

Medical management of pituitary adenomas: the special case of management of the pregnant woman

The development of efficacious surgical and medical therapies for pituitary adenomas as well as the improvement of hormone therapy for ovulation induction has made pregnancy possible for women harboring pituitary tumors. However, gestational risks due to the possibility of tumor growth during pregnancy, mainly in women with macroadenomas, raise a concern. Bromocriptine has a well-established role for prolactinoma treatment before and during pregnancy, even when a symptomatic tumor increase occurs. It can also be used in acromegaly, despite its poorer results. Somatostatin analogs have been used in acromegaly even during pregnancy with uneventful outcomes, but their safety in pregnancy is not well established, yet. The largest experience with medical treatment for Cushing's disease during pregnancy involves metyrapone, a steroidogenesis inhibitor, without descriptions of congenital abnormalities. Concerning clinically non-functioning pituitary tumors, ovulation induction or even in vitro fertilization are frequently needed. The purpose of this review is to provide an update on therapeutic strategies to restore fertility as well as gestational and post-gestational management of patients with pituitary adenomas, focusing mainly on the role of medical treatment for different tumor types.

Pathogenesis and prevalence of hypertension in acromegaly

Hypertension is an important complication of acromegaly, contributing to the increased morbidity and mortality of this condition. Prevalence of hypertension in acromegalic patients is about 35%, ranging from 18 to 60% in different clinical series, and the incidence is higher than in the general population. The lowering of blood pressure observed concomitantly with the reduction in GH levels after successful therapy for acromegaly suggests a relationship between GH and/or IGF-I excess and hypertension. The exact mechanisms underlying the development of hypertension in acromegaly are still not clear but may include several factors depending on the chronic exposure to GH and/or IGF-I excess. Experimental and clinical studies suggest that the anti-natriuretic action of GH (due to direct renal action of GH or IGF-I and/or to indirect, systemic GH or IGF-I-mediated mechanisms) may play a role in the pathogenesis of hypertension. Acromegaly is frequently associated with insulin resistance and hyperinsulinaemia which may induce hypertension by stimulating renal sodium absorption and sympathetic nervous activity. Whether sympathetic tone is altered in acromegalic hypertensive patients remains a matter of debate. Recent studies indicate that an increased sympathetic tone and/or abnormalities in the circadian activity of sympathetic system could play an important role in development and/or maintenance of elevated blood pressure in acromegaly, and may partially account for the increased risk of cardiovascular complications. Acromegalic cardiomiopathy may also concur to elevate blood pressure and can be aggravated by the coexistence of hypertension. Finally, a role of GH and IGF-I as vascular growth factors cannot be excluded. In conclusion, acromegaly is associated with hypertension, but there is still no real consensus in the literature on the mechanisms behind the development of the high blood pressure.