If MRI of the pituitary confirms a tumor in the patient with acromegaly, what issues other than the metabolic effects of excessive GH should be considered?
1 Is the tumor making any other pituitary hormones besides GH? For example, many GH-secreting tumors also produce prolactin; rare tumors also make thyroid-stimulating hormone or other pituitary hormones. In patients with acromegaly, prolactin levels should be measured, as well as other hormones when clinically indicated.
2 Is the tumor interfering with the normal function of the pituitary gland? Specifically, does the patient have impaired thyroid, adrenal, and gonadal function? Does the patient have diabetes insipidus? It is important to diagnose and treat pituitary insufficiency before therapy for the excessive secretion of GH, especially if the patient is scheduled for surgery.
3 Is the tumor causing effects owing to its size and location? Possible effects include headache, visual field disturbances, and extraocular movement abnormalities. Formal visual fields examination should be carried out in patients with large pituitary tumors.