5: Pituitary Gland disorders Flashcards
Macroadenoma
> 10mm
- headache
- visual disturbances
- cranial nerve palsies
- pressure atrophy of functioning cells-> hypopituitarism
Microadenoma
Incidentaloma
Adenomas- dx
MRI- confirmatory*
Adenoma- rx
Meds
Surgery- Transphenoidal surgery
Prolactinoma- sx
Women- menstrual irregularities and infertility lead to earlier recognition. Vaginal dryness, hot flashes, irritability, osteopenia, hirsutism
Men- decreased libido and erectile dysfunction often attributed to other causes, leading to delayed recognition. Visual impairment, headache, hypopituitarism
Prolactinoma- dx
basal PRL levels >200g/mL
MRI
Prolactinoma- rx
Dopamine agonist
-Bromocriptine
-Cabergoline
Transphenoidal surgery (if intolerant/resistant to meds)
GH cell adenoma- sx
Childhood- gigantism Adults- acromegaly -widening of hands and feet -coarsening of facial features -enlargement of frontal sinuses
GH cell adenoma- dx
MRI
serum IGF-1- elevated
Oral glucose tolerance test (OGTT)- definitive test**
-positive result: failure of GH to decrease to <1ng/mL after ingesting 50-100g of glucose***
GH cell adenoma- rx
Trans-sphenoidal microsurgery (initial therapy of choice)- rapid results
Radiotherapy- results only 20yrs after, usually reserved for post-surgical management to prevent re-growth of residual tumor
Meds
-Octreotide
-Bromocriptine
-Pegvisomant (GH receptor antagonist)
ACTH cell adenoma- dx
Elevated urinary free cortisol
Elevated nighttime plasma or salivary cortisol
Normal or elevated ACTH
Suppression during the high-dose dexamethasone test
-Low dose (0.5mg q 6h): both; cortisol > 5micro g/dL
-High dose (2mg q 6h):
–ACTH secreting pituitary tumor; < 5micro g/dL
–Ectopic ACTH secretion; > 5micro g/dL
ACTH cell adenoma- rx
- Trans-sphenoid resection**(TOC)
- Radiation therapy
- Meds; ones that block steroid synthesis (Ketoconazole, Metyrapone, Aminoglutethimide, Nifepristone, Trilostane)
Gonadotropin cell adenoma- sx
- sx of local pressure (headache, visual disturbance)
- Hypogonadism (due to constant secretion-> inhibition)
Gonadotropin cell adenoma- dx
- increased gonadotropin (FSH>LH) in the setting of a pituitary mass
- decreased testosterone despite normal or increased LH
- TRH administration stimulations LH b subunit secretion
- retrospective immunohistochemical analysis of surgically resected tumor tissue*
Gonadotropin cell adenoma- rx
- Transphenoidal surgical removal (primary rx)
- Radiotherapy
TSH-secreting pituitary tumors- rx
- Transphenoidal surgery
- Octreotide
- Iodine-131 thyroid ablation or thyroid surgery
Hypopituitarism- cc
1: Pituitary adenoma (MC in adults)
2: Craniopharyngioma
3: Sheehan syndrome
4: Putuitary apoplexy
5: Head trauma
6: Empty sella syndrome
7: Infiltrative disease (Wegner, Sarcoidosis)
8: Cranial radiotherapy to treat non-pituitary tumors
GH deficiency in children- dx
- Examining response to provocative stimuli (ie; exercise, insulin-induced hypoglycemia [insulin tolerance test: ITT], IGF-1 tests that normally increase GH> 7ug/L)
- random GH measurement not done-> pulsatile secretion)**
Insulin tolerance test (ITT)
GOLD standard for assessing GH reserve
- hypoglycemia is a potent stimulus for GH secretion
- Normal peak GH at 60mins:
- ->5ng/mL in adults
- ->10ng/mg in children
GH deficiency in adult- usual sequential order of hormone loss
GH> FSH/LH> TSH> ACTH
- in case of pituitary lesion
GH deficiency in adult- dx
- Insulin tolerance test (choice)**
- Alternative stimulation tests: Arginine & GHRH
ACTH deficiency- dx
- ITT (choice)**
- concomitant Cortisol and ACTH determination (<3ug/dL @8am: adrenal insufficiency)
- random basal ACTH is unreliable: short half life and pulsatile secretion
ACTH deficiency- rx
- Hydrocortisone
- Cortisone acetate
- Prednisone
- -dose increased 5- to 10- fold in times of stress (surgery)
- -dose doubled during minor illness
- —adrenal insufficiency should be rx upon suspicion and definitive dx made post-therapy
Gonadotropin deficiency- dx
Women- basal estradiol, LH, FSH
Men- Testosterone (total; free), LH, FSH
–low or inappropriately normal serum gonadotropin levels in the setting of low sex hormone concentrations
MRI
Prolactin deficiency- info
Elevated prolactin levels may be present in hypothalamic disorders
-increased inhibitory effects of dopamine
TRH test; normal: prolactin level increases after TRH administration (hypopituitarism fails to increase prolactin)
Diabetes insipidus- dx: water deprivation test
Central DI: Supressed ADH
Nephrogenic DI: normal or increased level of ADH
Primary polydipsia: normal or increased level of ADH
Diabetes insipidus- rx
Central: desmopressin acetate (DDAVP)
Nephro: diuretics with dietary salt restriction
