Medical treatment of acromegaly: comorbidities and their reversibility by somatostatin analogs.
Relief of symptoms can be achieved following surgery for growth hormone (GH)-secreting adenomas, as well as after pharmacological therapy with somatostatin analogs. Recently, long-acting somatostatin analog depot formulations, octreotide LAR and lanreotide SR have become available. Somatostatin analogs control GH/insulin-like growth factor (IGF)-1 excess, induce tumor shrinkage in a high proportion of patients, improve symptoms of acromegaly with relatively limited side effects and are successfully administered in patients not suitable for surgery. Furthermore, preoperative somatostatin analogs have been suggested to improve outcome for tumors with limited invasiveness, while surgical tumor debulking in cases that are, at least partially, somatostatin resistant, increases the achievement of normal IGF-1 levels by postoperative somatostatin analog treatment. Effective control of hypertension, as well as diabetes, is mandatory in order to reduce the increased vascular morbidity/mortality. Control of GH/IGF-1 excess generally improves glucose metabolism. Somatostatin analogs improve insulin sensitivity, exerting, however, a concomitant direct inhibitory effect on insulin secretion, with a net balance leaning towards a deterioration in glucose homeostasis. As a result, oral insulin secretagogues (and/or insulin) should probably be preferred to insulin sensitizers in acromegalic patients developing diabetes while on somatostatin analogs. Nevertheless, glucose tolerance remains normal in most of the nondiabetic acromegalic patients, while diabetic acromegalic patients on insulin are at risk for hypoglycemia during initiation of somatostatin analog therapy. Although successful management of acromegaly has been associated with improvement in morphological and functional parameters of cardiomyopathy, limited and conflicting information is available regarding the effect on blood pressure control. Contradictory results have also been reported regarding sleep hypopnea or apnea in treated acromegalic patients. As acromegalic skeletal abnormalities are rather irreversible, apneic episodes may persist after normalization of hormonal levels. Aggressive therapy, including surgery, pharmacological treatment and, in some cases, pituitary irradiation, aiming at normalization of IGF-1 levels, is required for arthropathy management. Some improvement in pain, crepitus and range of motion has been observed after treatment with somatostatin analogs. Information on the impact of disease control, either by surgery or somatostatin analog treatment, on gonadal function is limited. Finally, the link between the hormonal/biochemical and the psychiatric/psychological features of acromegaly, as well as a potential basis for positive effects of somatostatin analog therapy remain unclear.
Tolis
George
G
Division of Endocrinology and Metabolism, Hippokrateion General Hospital, Athens, Greece.
Angelopoulos
Nicholas G
NG
Katounda
Eugenia
E
Rombopoulos
Grigorios
G
Kaltzidou
Victoria
V
Kaltsas
Dimitrios
D
Protonotariou
Anthi
A
Lytras
Aristides
A
D000172:Acromegaly / Q000097:blood / Q000150:complications* / Q000188:drug therapy* / Q000601:surgery; D000236:Adenoma / Q000097:blood / Q000150:complications / Q000188:drug therapy / Q000601:surgery; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D050260:Carbohydrate Metabolism / Q000187:drug effects / Q000502:physiology; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000188:drug therapy / Q000517:prevention & control; D007006:Hypogonadism / Q000150:complications / Q000188:drug therapy / Q000517:prevention & control; D007592:Joint Diseases / Q000150:complications / Q000188:drug therapy / Q000517:prevention & control; D015282:Octreotide / Q000627:therapeutic use; D010456:Peptides, Cyclic / Q000627:therapeutic use; D010911:Pituitary Neoplasms / Q000097:blood / Q000150:complications / Q000188:drug therapy / Q000601:surgery; D012891:Sleep Apnea Syndromes / Q000150:complications / Q000188:drug therapy / Q000517:prevention & control; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000627:therapeutic use*
D018931:Antineoplastic Agents, Hormonal; D010456:Peptides, Cyclic; C060347:lanreotide; D019382:Human Growth Hormone; D013004:Somatostatin; D015282:Octreotide