Thyroid Flashcards
what does GH hypersecretion lead to in childhood?
gigantism
what does GH hypersecretion lead to in adults
acromegaly
what most often causes hypersecretory GH
pituitary adenoma
ACTH levels are ________ in adrenal insufficiency because of the primary adrenal disorder.
normal to high
ACTH is ___________ in adrenal insufficiency secondary to hypothalamic-pituitary hypofunction
low to absent
what metabolism does GH affect?
carbohydrate metabolism
How do deficiencies of GH manifest in children?
growth delays and fasting hypoglycemia
in adults how do growth hormone deficiencies manifest?
abdominal girth
reduce strength
decreased lean body mass
cut off point between micro and macro adenomas
<1 cm is microadenoma
An amino acid secreted episodically by pituitary lactotrophs
Prolactin
what do estrogens increase?
PRL secretion
gluccocorticoids
Is PRL needed to maintain lactation after nursing has begun?
No
PRL levels greater than what are highly suggestive of PRL-secreting adenomas
> 200 ng/ml
what hormone is checked for growth hormone problems?
IGF-1
in men with a prolactinoma what will be suppressed?
testosterone
A glycoprotein hormone synthesized & secreted by pituitary thyrotroph cells .
Thyroid stimulating hormone (TSH)
Normal TSH level?
1.5-5.0
what do anterior pituitary deficiency result in?
leads to growth retardation, deficient or absent lactation, hypogonadism, hypothyroidism & adrenal insufficiency.
what are common causes of anterior pituitary deficiency
tumor, infarction, necrosis, infection, autoimmune inflammatory processes, certain Rx & genetic anomalies.
2 posterior pituitary hormones
oxytocin
ADH
Diagnostics of chronic for anterior pituitary deficiency
IGF-1; plasma testosterone, TSH, Free T4, and plasma cortisol response to synthetic ACTH
mot common functioning tumor
prolactinoma
Caused by pituitary adenoma causing excess GH or excess GHRH
Link to the MEN-I gene (Multiple Endocrine Neoplasia)
acromegaly
⇑ growth of jaw, hands, feet & internal organs
occurs if disease hits before closure of epiphyses
Gigantism
other random features of acromegaly
moist palms
CTS
deep, coarse voice
sleep apnea
most reliable lab study for possible acromegaly
IGF-1
most common presentation of prolactinoma
amenorrhea
Tx for acromegaly
endoscopic trans-sphenoidal surgery remains the treatment of choice
tx failure- sterotactic radiosurgery used in tx failures
is most galactorrhea due to prolatcinoma
no, only 40-45%
other txs besides surgery for acromegaly
dopamine agonists (bromocriptine, pergolide, cabergoline)
somatostatin
radidation
Short limbs & long narrow trunks, lg. head & mid-face hypoplasia & prominent brow
Intelligence is normal
achondroplastic dwarfism :)
complications of achondroplastic dwarfism
leg bowing
obesity
dental problems
frequent otitis media
Tx for prolactinoma
dopamine agonist- bromocriptine (qhs), cabergoline (2x weekly)
main side effect of dopamine agonists
naseau
signs of pituitary dwarfism
not apparent at birth
signs- micro-penis and hypoglycemia
gene mutation with achondroplastic dwarfs
mutations in FGFR3 gene
what does a lack of ADH cause
diabetes insipidus
diagnosis of diabetes insipidus
high serum osmolality >290 dilute and copious urine output polydipsia dehydration hypernatremia
tx for SIADH
DDAVP (synthetic vasopressin) intranasally that causes a 50% or greater increase in urine osmolality is diagnostic for diabetes insipidus
signs of prolactinoma in men
low sex drive
low energy
hot flashes
lab workup for men w/ low sex drive
total and free testosterone
LH/ FSH
prolactin
TSH
what may nephrogenic diabetes insipidus respond to
HCTZ or in combo w/ indomethacin
Syndrome of high plasma ADH levels decreasing the serum osmolality
( <280mOsm/kg) , high urine osmolality
SIADH
what must you exclude before a dx of SIADH
Diagnosis must first exclude nephrotic syndrome, CHF, & cirrhosis by confirming thyroid, adrenal, renal & cardiac status.
what happens during a glucose tolerance test w/ acromegaly
growth hormone doesn’t drop
The most common cause of ACTH-independent Cushing’s Disease
adrenal adenoma (<3 cm in diameter)
3 hormones released by adrenal
aldosterone
cortisol
epinephrine
what is cortisol involved in
stress hormone
sleep
what 3 hormones are involved in circadian rhythms
cortisol
growth hormone
adrenaline
common characteristics of cushings
truncal obesity, hypertension, striae, ecchymoses, proximal muscle weakness, hypokalemia, osteoporosis, and infertility.
what can cause false + labs for cushing’s?
anti-seizure Rx
oral contraceptives
rifampin
spironolocatone
first test is suspecting cushings
24 urinary free cortisol
if you order a 24 urine what else do you need to order
creatinine to know it it was an adequate collection
2nd screening test for cushing’s
2mg dexamethasone suppression test
if it hasn’t suppressed that is abnormal
3rd screening test for cushing’s
8 mg dexamethasone and then check if it is suppressed (points to adrenal source)
if suppression did occur with high dexamethasone test where do you suspect the tumor to be?
pituitary
other conditions that can create a hypercortisol state
Depression, Alcoholism, Anorexia Nervosa, Panic disorder, & Withdrawal syndromes (from drugs of abuse - narcotics & alcohol)
what is cosyntropin
synthetic ACTH
with primary adrenal insufficiency what hormone will be high?
ACTH and MSH
will have hyperpigmentation
present w/ HTH difficult to control
Persistent hypokalemia
Impaired glucose tolerance
hyperaldosteronism
workup of hyperaldosteronism
Aldosterone suppression test combined with increased NaCl (po or IV)
Spironolactone relieves - is diagnostic too
CT of adrenals (hyperplasia or carcinoma)
who are most affected by hyperaldosternism
women
most common cause of primary adrenal insufficiency worldwide
TB autoimmune adrenalitis (industralized nations)
what conditions is prednisone use chronically and can lead to iatrogenic cushings
asthma
RA
IBD
what is myxedema
dough consistency due to high TSH (hypothyroidism)
other manifestations of myxedema
lethargy
thick tongue
slow mental functioning
coarse hair
diagnostics for panhypopituiarism
IGF-1 (low) plasma testosterone (low) TSH (normal-low) Free T4 (low) plasma cortisol response to synthetic ACTH
benign tumor but when removed could possibly affect pituitary
craniopharyngioma
what usually causes hyperaldosteronism
adenoma
screening test for hyperaldosteronism
normalize the K+
then plasma, renin serum aldosterone (want ratio, will be high)
24 hour urine (look for aldosterone)
CT scan of adrenal glands (no contrast)
test for hyperaldosteronism
saline suppression test
check aldosterone level before and after, confirmed if it doesn’t suppress
what can cause hyperaldosteronism
bilateral adrenal hyperplasia or carcinoma
tx for hyperaldosteronism
spironolactone
what causes secondary hyperaldosteronism
from failure of pituitary secretion of ACTH
women affected more
main dx lab for addison’s
Low 8AM plasma cortisol (< 5mg/dL) with elevated ACTH (> 200mg/dL)
high ACTH level
high plasma renin/low plasma aldosterone
test for pheochromocytoma
plasma free metanephrine and
24 hour urine catecholamines
confirm w/ CT or MRI
Tumor producing excess of catecholamines & their metabolites
pheochromocytoma
how do patients w/ a pheochromocytoma present
Nearly all affected pts have episodic hypertension while over 50% have sustained HTN with associated headache, sweating, & palpitations.
what are pheos associated w/?
Neurofibromatosis
Von Hippel-Lindau retinal angiomatosis
Cerebellar hemangioblastoma
Multiple endocrine neoplasia
treatment of choice for pheo
surgery
what must be done before surgery for a pheo
B/P controlled for1-2 weeks
use alpha-adrenergic blockers (sins) and beta blockers
Crisis tx for pheochromocytoma
regitine or nitroprusside to control BP
