GH1 and growth hormone-producing pituitary gland adenoma: Pituitary tumours are also classified according to their hormonal production as: lactotrophinomas (secreting prolactin), that comprise ∼50% of tumours; gonadotrophinomas (secreting follicle stimulating hormone (FSH) or lutenising hormone (LH), but predominantly non-functioning), comprising ∼30% of tumours; somatotrophinomas (secreting growth hormone (GH)), comprising 15–20% of tumours; corticotrophinomas (secreting adrenocorticotropic hormone (ACTH)), comprising 5–10% of tumours; and thyrotrophinomas (secreting thyroid stimulating hormone (TSH)), comprising <1% of tumours.