Multivariate analysis showed that the increased bilateral ICAs distance was associated with disease duration (odds ratio = 1.01, 95% confidence interval = 1.01–1.02, P = 0.005) and refractory pituitary adenoma (odds ratio = 9.8, 95% confidence interval = 1.1–88.7, P = 0.043) but not with level of growth hormone (GH), insulin-like growth factor-1 (IGF-1) and adenoma size in acromegaly. This evidence concerns the gene GH1 and pituitary gland adenoma.