Serum Levels of 20 Kilodalton Human Growth Hormone (20K-hGH) in Patients with Acromegaly before and after Treatment with Octreotide and Transsphenoidal Surgery

摘要

References(16) Cited-By(2) Circulating human GH (hGH) consists of several molecular isoforms. It was previously reported that the proportion of 20 kilodalton hGH (20K-hGH) was elevated in the serum of patients with active acromegaly. In this study, we investigated the effects of octreotide and transsphenoidal adenomectomy on the proportion of 20K-hGH in the serum of 7 acromegalic patients. To achieve an acute effect, octreotide (100 μg) was subcutaneously injected as a bolus. To observe the chronic effects of octreotide therapy and surgery, serum samples were obtained by repetitive blood sampling before and 3 to 8 weeks after treatment. Serum levels of 20K-hGH and 22 kilodalton hGH (22K-hGH) were determined by specific enzyme-linked immunosorbent assay. A bolus injection of octreotide elicited a parallel decrease in serum 22K-hGH and 20K-hGH, resulting in an unchanged proportion of 20K-hGH to total circulating hGH. The proportion of 20K-hGH was decreased in 4 of 4 patients 4 to 7 weeks after surgery and in 2 of 4 patients after chronic treatment with octreotide for 3 to 8 weeks. The proportion of serum 20K-hGH was positively related to mean serum 20K-hGH as well as serum total hGH levels, but not with serum IGF-I levels. These findings suggest that high serum levels of 20K-hGH or total hGH per se might elicit a chronic change in the clearance kinetics of 20K-hGH and increase the proportion of 20K-hGH in acromegalic patients.