| What are the types of secretory pituitary adenomas? | Gonadotropic-Releasing Adenoma, Growth-Hormone Releasing Adenoma, Thyrotropin Releasing Adenoma |
| What is the gonadotropin cycle? | GnRH released from hypothalamus, releases LH and FSH from pituitary then go to gonads to produces sex hormones for puberty and reproduction. |
| What are the hormonal characteristics of pituitary hormones? | all gonadotropins and thyroid stimulating have same a subunit but different beta subunit. |
| What are gonadotropin-releasing pituitary tumors? | They are tumors arising from cells producing LH and FSH, usually non-functional clinically (null adenoma) with no elevation of gonadotrophins, but causes pathology to gonadotroph cells, with elevated a subunit detected by Immunohistochem. |
| How is the clinical presentation of gonadotropin-releasing pituitary tumors? | Usually incidentaloma (MRI, CT of sinuses we detect it)
If large enough they may cause local compression and visual defects.
May present as deficiency in one or more pituitary hormones (most commonly GNh deficiency (gonadotrophin def) |
| What are functioning gonadotroph tumors? | very very rare, Maybe FSH-producing or LH-producing
If FSH-producing it may cause pelvic pain due to overstimulation of ovaries, irregular cycle and PCOS
If LH-producing it may cause elevation of testosterone (hirsutism) |
| How is the evaluation of gonadotroph producing adenomas? | MRI, visual field exam, pituitary hormone levels
We should always follow it up even if incidentaloma.
If nonfunctioning microadenoma we observe it, if macroadenoma we perform transsphenoidal surgery to remove it |
| What is acromegaly? | Excess GH causing peripheral enlargement of an adult, caused by somatotropin excess.
It is a very rare disorder (3-4 / million) |
| How is the pathogenesis of acromegaly? | Elevated GH by adenoma and increased IGF-1, basal levels of GH are high, although the pulsatile pattern of GH release kept intact.
Usually from pituitary (95%), pancreas and hypothalamus. |
| How do we diagnose acromegaly? | Usually it appears very symptomatic, no need for labs
Used labs are GH level >1microg/L after glucose load, and serum IGF-1 elevated. |
| What are the main causes of acromegaly? | -pituitary acromegaly (adenoma)
-Ectopic GH secretion (maybe in pituitary or out)
-Excess GHRH
(pituitary carcinoma is very rare) |
| What is pituitary acromegaly? | more than 95% of acromegaly pt have it, could be pure GH-cell adenoma (densely stained GH granules --> slow growing adenoma, if sparsely stained then fast growing, usually benign)
or mixed GH and PRL-cell adenoma (grow rapidly invasive and prominent hyperprolactinemia features) |
| What are the causes of pituitary acromegaly? | Disordered Somatotroph Cell Function (activated oncogene for somatotroph cells, stimulate GHRH and GHS, maybe germline mutation (FIPA- mutation in supressor))
Disordered GHRH Secretion or Action
Ectopic Pituitary Adenomas (GH releasing from remnants of sphenoid sinus, petrous bone, nasopharynx, very rarely carcinoma) |
| What is extrapituitary acromegaly? | Ectopic acromegaly, rare less than 1% of pt, produced in islet cell tumors or non-hodgkins lymphoma |
| What is thalamic acromegaly? | GHRH hypersecretion |
| What is MacCune-Albright Syndrome? | Rare hypersecretory syndrome, GNAS gene mutation, G protein activating adenylyl cyclase always on, it is a random mutation and not inherited (mosaic) |
| What is multiple endocrine neoplasia? | MEN1 (menin tumor suppressor 1) inactivation leads to sporadic GH-adenoma (if in pancreas insulinoma, in gastric gastrinoma (seen in PUD)) |
| What are the clinical features of acromegaly? | Slow onset -6-10 years, 3% altered facial appearance, acral enlargement (97%) hyperhidrosis , large fleshy lips and nose, spade like hands, frontal skull bossing, visceromegaly (all organs), increase shoe hand and hat size
May cause bilateral carpal tunnel/ skin tags/ polyps/ osteoporosis |
| What is gigantism? | Excess GH in childhood, tall, 20% have MacCune-Albright, can cause bilateral carpal tunnel, arthropathies, spinal involvement (kyphosis), debilitating osteoarthritis, skin tags (polyps), HTN, hyperhidrosis. |
| What are the endocrine complications of acromegaly? | 30% elevated PRL, prediabetic/ diabetic (IGF-1 increase), thyroid cell growth increase
It may compress pituitary causing hypopituitarism, secondary hypothyroid/ adrenal insufficiency, gonadal dysfunction. |
| What are thyrotropin-releasing tumors? | TSH-release, very rare 1%, mostly benign, 88% macroadenomas, present with symptoms from tumor growth mostly, and less likely signs of hyperthyroid + 2/3 have goiter
Evaluated by T4, T3 and TSH levels + MRI |
