Does Growth Hormone directly affect peripheral tissues? No. Most (although not all) effects of GH are mediated by another hormone called insulin-like growth factor-1 (IGF-1). IGF-1 is made by the liver and other organs in response to stimulation by GH. IGF-1 feeds back to the pituitary gland and suppresses GH secretion. Unlike GH, IGF-1 has …
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How growth hormone levels normally regulated Pituitary secretion of GH is primarily regulated by two hypothalamic hormones: stimulatory GH-releasing hormone (GHRH) and inhibitory somatostatin. Secretion of GH is also affected by adrenergic and dopaminergic hormones, as well as by other central nervous system and peripheral factors. GH is secreted from the pituitary gland in pulses …
What is the normal function of growth hormone in children and adults? In children, GH is responsible for linear growth. In children and adults, GH has many effects on intermediary metabolism, including protein synthesis and nitrogen balance, carbohydrate metabolism, lipolysis, and calcium homeostasis.
Are prolactinomas ever malignant? Malignant prolactinomas account for about 1 to 2 per 1000 pituitary adenomas. Features that may suggest malignancy are loss of responsivity to dopamine agonists in a previously responsive tumor, rapid regrowth after surgery, repeated operations for tumor growth and rising prolactin levels, the development of metastases, and high Ki-67 labeling. Aside …
What is a giant prolactinoma? Giant prolactinomas are defined as prolactinomas > 4 cm in size. Cabergoline is usually the initial treatment of choice, although high doses may be required; surgery is indicated for cabergoline-resistant cases, and radiation therapy can be added if the tumor progresses. If progression continues despite these measures, temozolomide, an alkylating …
When is radiotherapy indicated to treat a prolactin secreting tumor? Radiotherapy has rarely been used because hypopituitarism is a common side effect, generally occurring within a few years. This complication is of critical concern, particularly in patients undergoing treatment for infertility. However, radiotherapy may be a useful adjunct in patients who require additional treatment after …
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When is surgical removal of a prolactin secreting tumor indicated? With the availability of dopamine agonists, surgery has become a secondary choice in the treatment of prolactin-secreting tumors, particularly because the long-term surgical cure rate for large tumors is only 25% to 50%. The principal indications for surgical treatment of a prolactin-secreting tumor are intolerance …
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