Association of total, acylated and unacylated ghrelin with apolipoprotein A1 and insulin concentrations in acromegalic patients.

BACKGROUND: Ghrelin is a hormone that occurs in acylated (AG) or unacylated (UG) form. Ghrelin strongly stimulates growth hormone (GH) secretion from anterior pituitary, as well as regulates the energy balance and various metabolic parameters. Increased consideration is given to UG, thought to be inactive.

OBJECTIVES: We aimed to evaluate the levels of total ghrelin, AG and UG in medically naive and treated patients with biochemically active acromegaly, with respect to variables of lipid and glucose metabolism.

MATERIAL AND METHODS: We studied total ghrelin, AG and calculated UG levels in a group of 24 patients with active acromegaly and 15 healthy controls. Plasma levels of GH, insulin-like growth factor 1 (IGF-1), insulin, glucose, total cholesterol (TC), high-density lipoprotein (HDL) cholesterol and calculated low-density lipoprotein (LDL) cholesterol, triglycerides (TG), apolipoproteins A1 (APO A1), and B-100 (APO B-100) were measured.

RESULTS: Patients with acromegaly revealed lower levels of total ghrelin than healthy controls. In pooled data of all subgroups, simple linear regression analysis revealed that total ghrelin concentration was significantly associated with APO A1 concentration (β = 0.8087; p = 0.0315) and AG concentration was significantly associated with fasting insulin concentration (β = 15.5183; p = 0.011). There was an inverse association between UG and the patients' age, and positive association between UG and APO A1.

CONCLUSIONS: Our results suggest that ghrelin may influences metabolic disturbances in acromegaly. It seems that the assessment of AG and UG is superior to total ghrelin measurement. Mechanisms regulating ghrelin acylation and function of each form need elucidation in order to improve diagnostics and treatment of metabolic disturbances, not only acromegaly.