Current diagnosis of acromegaly

Abstract

Acromegaly is a rare and chronic condition that is characterized by sustained unregulated hypersecretion of growth hormone (GH). More than 99% of the cases of acromegaly are due to a pathologic proliferation of pituitary somatotrophs presenting in the form of a pituitary adenoma. The excessive amounts of GH and its target hormone, insulin like growth factor-1 (IGF-1) cause metabolic changes and tissue enlargement that, collectively, lead to significant morbidity and a two to threefold increase in mortality. Thus, early diagnosis has proved to be crucial to improve survival and quality of life in this condition. The development of radioimmunoassay (RIA) in the 1960s provided clinicians with a biochemical tool to diagnose acromegaly. Many limitations were inherent to this methodology which necessitated the development of more sensitive tools, such as immunoradiometric (IRMA) or immunoluminometric (ILMA) assays for GH and IGF-1 measurements. These newer assays have not come without imperfections. The reference ranges to describe normalcy of the somatotropic axis and the biochemical criteria of "cure" of acromegaly are areas of great debate. Nevertheless, the current international consensus agrees that the diagnosis of acromegaly should be based on both clinical presentation and biochemical data.