Due to the pulsatile characteristic of pituitary hormone secretion, its involvement in the acute response to stress and feed-back mechanisms with hormones of peripheral glands, baseline circulating levels of many pituitary hormones may significantly overlap between normal subjects and patients with pituitary disease. Therefore pituitary testing has been widely used for the diagnosis and follow-up of pituitary disease.
For example, provocative tests are frequently used in the diagnosis of adult GH deficiency (GHD), because normal IGF1 levels do not rule out severe GHD. The insulin tolerance test (ITT) is still considered as the test of reference but it should be recognized that other, less bothersome, tests are as reliable as the ITT, for example the GHRH/arginine stimulation test.
The endocrine nurse has an important role in conducting these tests. This role involves more than just administrating the diagnostic agent and blood sampling. Firstly, the endocrine nurse has a job in providing information to the patient about the purpose, adverse effects, and practical execution of the test. Secondly, it is very important that the endocrine nurse observes the patient well and that he/she is able to act quickly and correctly upon complications or problems. The problems that the endocrine nurse may face are divers and require an adequate approach, without affecting the test. Any problems should be clearly communicated with the treating endocrinologist. Thirdly, the endocrine nurse should guide the patient during this whole process. Finally, the endocrine nurse has a role in identifying and solving structural problems. In addition the nurse can take responsibility in writing and updating protocols in collaboration with an endocrinologist. All of this demands knowledge of anatomy and physiology of the endocrine system, knowledge about the various function tests and knowledge about blood sampling techniques and laboratory techniques.