Pituitary Macroadenoma

A pituitary macroadenoma is a relatively large, typically benign growth in the pituitary gland — a small structure at the base of the brain that produces hormones influencing metabolism, growth, and reproduction. The term 'macro' indicates a tumour larger than one centimetre, which may exert physical pressure on surrounding brain tissue as well as disrupt normal hormone production. This can lead to effects both from excess hormone release and from compression of nearby structures. Owners often become aware of the possibility through changes in drinking and urination, appetite, energy, or behaviour, or because investigations for another concern have revealed an abnormality on blood tests or imaging. In some cases, neurological signs such as altered awareness, circling, or changes in vision may prompt the initial visit. The presentation depends on which hormones are affected, how large the growth has become, and which adjacent structures are influenced. This page explores the signals that may be observed, the mechanisms underlying those signals, the investigations used to characterise the growth and its effects, and the range of approaches that exist — from monitoring and hormone management to radiation and surgery. Each section is written to help you understand what may be happening and what conversations may follow.