GHRH and neuroendocrine neoplasm: Interestingly the risk of altered glucose metabolism is also impacted by the tumor type causing acromegaly.30 In exceptional cases GH excess may be caused by a hypothalamic GHRH-producing gangliocytoma with or without an associated PitNET, or by ectopic GHRH or GH production by a neuroendocrine neoplasm elsewhere in the body.