The Acylated/Unacylated Ghrelin Ratio Is Similar in Patients With Acromegaly During Different Treatment Regimens.

Abstract

Data on plasma acylated ghrelin (AG) and unacylated ghrelin (UAG) levels in acromegaly are limited. High AG/UAG ratios are linked with type 2 diabetes, obesity, and hyperphagia (e.g., in Prader-Willi syndrome). To assess fasting plasma AG and UAG levels, and the AG/UAG ratio in acromegaly patients receiving combination treatment of long-acting somatostatin analogs (LA-SSAs) and pegvisomant (PEGV; n = 60). We used as controls acromegaly patients whose disease was controlled with PEGV monotherapy and medically naïve patients with active acromegaly. Fasting venous blood samples were collected and directly stabilized to inhibit deacylation of AG. Plasma AG and UAG levels were determined by double-antibody sandwich enzyme immunoassay, and the AG/UAG ratio was calculated. Plasma AG and UAG levels were significantly lower in patients with acromegaly receiving combination treatment [median, interquartile range (IQR): AG: 8.5 pg/mL, 2.9 to 21.1 pg/mL; UAG: 26.9 pg/mL, 11.2 to 42.1 pg/mL] compared with patients using PEGV alone [AG: 60.5 pg/mL (IQR, 58.8 to 77.4 pg/mL); UAG: 153.7 pg/mL (IQR, 127.3 to 196.0 pg/mL)] and medically naïve patients with acromegaly [AG: 24.0 pg/mL (IQR, 12.6 to 49.7 pg/mL); UAG: 56.3 pg/mL (IQR, 43.4 to 61.5 pg/mL)]. However, AG/UAG ratios were similar in all groups. Although plasma AG and UAG are suppressed during combination treatment with LA-SSAs and PEGV, the AG/UAG ratio remained similar. This shows that SSAs decrease both AG and UAG levels, which suggests that they do not alter metabolism significantly in acromegaly patients.