Relationship of Decreased Circulating Apelin Levels with Growth Hormone, Insulin-like Growth Factor, Carotid Intima-media Thickness, and Epicardial Fat Thickness in Acromegaly

Objective: Acromegaly is a rare disorder that results from an overproduction of growth hormone. Patients with acromegaly are highly susceptible to the risk of vascular diseases and metabolic dysfunctions. Apelin, an adipose tissue-derived peptide, is related to insulin resistance, metabolic and cardiovascular disorders. This study aimed to investigate apelin level alterations in subjects with active acromegaly, controlled acromegaly and in subjects without acromegaly, employed as controls, and to identify the presence of any possible relationship between apelin and hormonal or cardio-metabolic parameters. Material and Methods: A total of 42 active and 32 controlled acromegalic patients, and 40 age-and body mass index-matched controls were recruited in this cross-sectional study. The hormonal and metabolic characteristics of the subjects as well as the carotid intima-media thickness and epicardial fat thickness were thoroughly evaluated. Apelin levels were also measured using ELISA methods. Results: Circulating levels of apelin were found to be significantly lower in the acromegalic subjects as compared to that in the controls. Moreover, active acromegalic subjects showed decreased apelin levels as compared to the controlled acromegalic subjects. Apelin demonstrated a negative correlation with insulin resistance, carotid intima-media thickness, epicardial fat thickness, body mass index as well as growth hormone and insulin-like growth factor-1 in subjects with acromegaly. Furthermore, an independent negative correlation was found between apelin levels and carotid intima-media thickness & epicardial fat thickness by the multivariate regression analysis. Conclusion: Decrease in circulating levels of apelin is associated with cardiovascular risk markers like carotid intima-media thickness and epicardial fat thickness and also has a negative correlation with growth hormone and insulin-like growth factor-1 in subjects with acromegaly.