Lipid metabolism in acromegalic patients before and after selective pituitary adenomectomy

Lipid metabolism was studied in 16 acromegalic patients who all underwent transsphenoidal selective pituitary adenomectomy (SPA). Before the operation, their serum lipid levels correlated with none of the basal levels of serum growth hormone (GH), basal levels of plasma somatomedin-C (SM-C), fasting levels of plasma glucose (FPG), peak levels of plasma glucose (PGp) or basal and peak levels of serum immunoreactive insulin (IRIb and IRIp, resp.) in the oral glucose tolerance test (OGTT), and obesity indices. The serum GH levels as well as plasma SM-C levels in the group with decreased serum high density lipoprotein-cholesterol (HDL-C) differed greatly from those of the normal HDL-C group. However, there was no significant difference in either serum GH or plasma SM-C between groups with and without metabolic abnormality of any other lipid examined. After the operation, the basal levels of serum GH and plasma SM-C decreased significantly. In conjunction with these changes, PGp, serum IRIb, serum triglyceride (TG), non-esterified fatty acid (NEFA) and very low density lipoprotein (VLDL) decreased significantly. In contrast, serum HDL-C increased significantly. However, FPG, serum IRIp, obesity indices, serum total cholesterol (TC) and serum low density lipoprotein (LDL) showed no significant change. There were no significant differences in the levels of any serum lipid either before or after surgery among the diabetic, borderline and normal types defined by the preoperative OGTT patterns. Atherogenic indices (AIs) decreased significantly and returned to normal postoperatively. These results suggest that obesity or secondary diabetes is not a direct cause of hyperlipidemia in acromegaly. The prognosis of acromegaly is affected by arteriosclerotic complications. It is intriguing, therefore, that AIs were normalized by transsphenoidal SPA. Being rather a safe procedure, it can be performed without hesitation, aside from a conservative treatment.