Endocrine Abstracts

Growth hormone (GH) and insulin-like growth factor-I (IGF-I) have important metabolic actions. GH/IGF-I excess and GH deficiency are each associated with ‘opposing’ comorbidities that often mirror one another. Cardiac and vascular comorbidity demonstrates that ‘too much’ may be as bad as ‘too little’. An association between acromegaly and increased cardiac mortality has long been claimed. This was based on epidemiological studies of patients treated a long time ago, when the current therapeutic tools were not available and radiotherapy was widely used. Recent epidemiological studies and data from acromegaly registries show no excess mortality and that cardiovascular disease is not the leading cause of death. This is thanks to effective treatment of acromegaly and aggressive management of comorbidities (diabetes, hypertension, lipid disorders). Observations resemble those in the background general population. In contrast, the clinical features of hypopituitarism with GH deficiency are more like those of the metabolic syndrome. This may explain why patients have an increased cardiovascular and cerebrovascular risk. GH treatment improves cardiovascular risk factors and is associated with a decreased incidence of cardiovascular (but not cerebrovascular) events in some studies. It also seems to be associated with a reduction in all-cause mortality in both sexes, but particularly in males, who attain the level of the general population. Thus, according to our homeostatic model, the GH/IGF-I axis follows the general rule that in medio stat virtus or ‘virtue stands in the middle’!