In those cases we call it tertiary hypopituitarism . **Diagnosis of pituitary deficiency by pituitary hormone stimulation test: All hormones are released in a pulsatile manner, and mostly they are 'stress' hormones. So hormones levels are different from minute to minute and from day to night (like cortisol level which is in the early morning two times more than its level around midnight). *Always we have to do what is called dynamic testing. as follows: *When we have hormonal deficiency (like Addison's), we try to stimulate the hormone [so we do stimulation test to confirm suspected deficiency]. *When we have hormonal excess (like cushing) we try to suppress the hormone [so we do suppression test to confirm suspected excess]. *Don’t memorize numbers in the following table!
7 Hormone Stimulation test agent N response Notes GH I.H. test (insulin induced hypoglycemia test) 0.1 uint L-dopa 250-500 Arginine 0.5 gm Clonidine test Glucagon test Serum GH > 10ng/ml at any time IH test is the Gold standard method. Prl TRH 100-500 Metoclopramide Doubling of baseline *Dopamine is prl antagonist and metaclopromide is dopamine antagonis! TSH TRH 500 ng Peak value >5 mu/ml *Nowadays, we don’t use stimulation test for thyroid because: *Thyroid measurements are enough for diagnosis. *Thyroid hormones don’t fluctuate in their values; they are fixed. LH & FSH GnRH 100mmg IV Doubling of the base line LH & FSH - ACTH I.H. TEST (short ACTH stimulation test cosyntropin test) Metyrapone test 2-3 gm po serum cortisol >20 ng/dl Serum 11-deoxycortisol level >8 ng/dl - **Treatment of hypopituitrism Treatment for life! (Except in GH deficiency: GH replacement therapy until the bone close. After that, it may be harmful and may induce acromegaly). Deficient hormone Therapy TSH L-thyroxin .05-.02 mg/d PO ACTH Hydrocortisone 20 mg/ m-10mg /e LH & FSH Men :testosterone Women :cyclic estrogen and progesterone (*)For fertility HCG, HMG GH 0.05 mg/kg – daily injection (*) people with secondary hypogonadism have the chance to be fertile, while primary hypogonadism patients don’t have any chance!
8 * Pituitary tumors: - Nearly always benign (i.e. adenomas) - Account for 10% of intracranial neoplasm * We have two types of adenomas: -Pituitary micro adenoma: intrasellar adenoma less than 1 cm in diameter. -Pituitary macro adenoma : those larger than 1 cm in diameter. - Pituitary micro adenoma is more more common than pituitary macroadenoma . *Type of pituitary tumors: * As we can see, the most common pituitary tumor is Prolactinoma , the 2 nd is nonfunctioning pituitary tumor , 3 rd is ACTH secreting adenoma , 4 th is Growth hormone secreting adenoma , 5 th is Plurihormonal secreting adenoma (i.e. secrets different hormones) , 6 th is LH or FSH secreting adenoma , 7 th is TSH secreting adenoma …. * When there's TSH secreting adenoma, then we'll have secondary thyrotoxicosis, but remember that TSH-secreting adenoma is rare with less than 1% of all pituitary tumors. * Clinical presentation of pituitary tumours: - Nonsecretory pituitary tumors may grow slowly, destroying normal pituitary function (hypopituitarism), or they may compress nearby structures and cause neurologic problems.
You've reached the end of your free preview.
Want to read all 22 pages?
- Winter '08
- Endocrine System, Cortisol, Pituitary adenoma