Endocrine Flashcards
Hormones secreted by the posterior pituitary? anterior pituitary?
Posterior - ADH, oxytocin; Anterior - ACTH, TSH, GH, LH, FSH, prolactin
post-partum trouble lactating, amenorrhea
Sheehan’s syndrome; due to pituitary ischemia following hemorrhage/hypotension during childbirth
adrenal insufficiency after meningitis
Waterhouse-Friderichsen syndrome; adrenal gland hemorrhage after meningococcal sepsis
Vascular supply of the adrenal gland?
Arterial (3) superior (inferior phrenic), middle (aorta), inferior (renal artery); Left adrenal vein (left renal vein), Right adrenal vein (IVC)
most common metastasis to adrenal gland
lung ca
components of the adrenal gland? what do they secrete?
cortex and medulla; cortex = GFR (glomerulosa - aldosterone, fasciulata - glucocorticoids, reticularis - androgens/estrogens); medulla = catecholamines
male with precocious puberty (or female with virilization), hyperkalemia, hypotension
21-hydroxylase deficiency (90% of congeintal adrenal hyperplasias) – leads to low aldosterone and high testosterone (increased 17-OH progesterone)
male with precocious puberty (or female with virilization), hypertension
11-hydroxylase deficiency, leads to salt saving (deoxycortisone acts as mineralcorticoid) and causes hypertension, high testosterone
hypokalemia, hypertension, weakness, polyuria - dx, lab findings
hyperaldosteronism (Conn’s syndrome), test w/ salt-load suppression test (urine aldo will stay high in primary), aldosterone:renin ratio >20
primary vs secondary hyperaldosteronism; causes, how to differentiate and tx?
primary (renin is low) aldo:renin ratio >20, most often caused by hyperplasia 60%, otherwise adenoma; secondary (renin is high) more common than primary, CHF, renal artery stenosis, liver failure, diuretics, renin tumor – adenoma tx w/ adrenalectomy, hyperplasia tx medical therapy (spironolactone, Ca blocker, K+, otherwise bilateral adrenalectomies)
hypotension, lethargy, hyperkalemia - dx, most common cause
hypocortisolism (adrenal insufficiency / Addison’s disease, most often caused by withdrawal of steroids, most common primary cause is autoimmune; decreased cortisol (due to high ACTH) and aldosterone – dx w/ cosyntropin test (give ACTH, measure urine cortisol, should remain low)
high cortisol levels, low ACTH – dx, next steps?
cortisol secreting lesion – i.e. adrenal adenoma or more commonly adrenal hyperplasia; adrenalectomy for adenoma, medical therapy first for hyperplasia (spironolactone which inhibits aldosterone)
high cortisol levels, high ACTH – dx, next steps?
pituitary adenoma or ectopic source of ACTH (i.e. small cell lung Ca); need to do high dose dexamethsone suppression test – if urine cortisol is suppressed = pituitary adenoma, if urine cortisol is not suppressed = ectopic producer of ACTH
most common non-iatrogenic cause of Cushing’s syndrome? tx?
pituitary adenoma – urine cortisol should be suppressed w/ either low or high dose dexamethasone suppression test – tx w/ transphenoidal resection, unrectable tumor treat w/ XRT
2 most common non-iatrogenic cause of Cushing’s syndrome? tx?
ectopic ACTH, most commonly from small cell lung ca - cortisol is not suppressed with either low or high dose dexamethasone suppression – tx w/ resection of primary
3 most common non-iatrogenic cause of Cushing’s syndrome? tx?
adrenal adenoma, get decreased ACTH, unregulated steroid production, tx w/ adrenalectomy
medication used for residual/recurrent or metastatic adrenocortical carcinoma
mitotane; inhibits adrenal cortex, induces adrenal atrophy – has poor response rates
where is epinephrine produced? what about for pheochromocytoma? what enzyme converts norepinephrine to epinephrine?
produced in adrenal medulla only; only adrenal pheochromocytomas will produced epinephrine; PMNT (phenylethanolamine N-methyltransferase) - enzyme found only in adrenal medulla
most common location of extra-adrenal pheochromocytoma
organ of Zuckerkandl (at aortic bifurcation)
hemodynamic management for pheochromocytoma
important to alpha blockade first (usually w/ phenoxybenzamine or terazosin) to avoid hypertensive crisis – then beta block if tachycardic/arrythmia – beta blockade without adequate alpha blockade leads to unopposed alpha stimulation, hypertensive crisis, stroke and heart failure
cell type of pheochromocytoma?
chromaffin cells (neural crest)
embryologic origin of thyroid gland? parathyroid glands?
thyroid from 1st and 2nd pharyngeal arches, superior parathyroid from 4th pharyngeal pouch, inferior parathyroid from 3rd pharyngeal pouch (Parathyroid from the Pouch)
what is the arterial and venous blood supply to the thyroid and where do they branch from
superior thyroid artery (1st branch of external carotid artery), inferior thyroid artery (off thyrocervical trunk / subclavian artery, supplies both parathyroids), Ima artery (arises from inominate/aorta to isthmus, 1% of pts); superior and middle thyroid vein (drain to internal jugular vein), inferior thyroid vein (drains into inominate vein)
what is the significance of the superior laryngeal nerve?
vagus branch, provides motor to cricothyroid muscle, lateral to thyroid lobes close to superior thyroid artery, injury results in loss of projection and easy voice fatigability
what is the general course of the recurrent laryngeal nerve?
runs posterior to thyroid lobe in the tracheoesophageal groove, often close to inferior thyroid artery, left RLN goes around aorta, right RLN goes around inominate artery
FNA of thyroid nodule shows follicular cells: dx/tx?
5-10% chance of malignancy, cannot differentiate between follicular cell adenoma, follicular cell hyperplasia, and follicular cell ca on FNA; tx w/ lobectomy vs total thyroidectomy
mechanism of propylthiouracil, methimazole? important side effects? use in pregnancy?
inhibits peroxidases and prevents iodine-tyrosine coupling – PTU is safe with pregnancy; both can cause aplastic anemia and agranulocytosis
most common type of thyroid ca, most common metastasis
papillary thyroid ca, rare mets to lung
general indication for total thyroidectomy?
for follicular/papillary bilateral lesions, multicentricity, history of XRT, positive margins, tumors >1 cm – total thyroidectomy w/ central neck node dissection for medullary thyroid cancer
FNA of thyroid nodule w/ amyloid deposits
medullary thyroid ca
1st manifestation of MEN2a (and MEN2b)
diarrhea/flushing from hyper-calcitonin medullary thyroid ca
cell type of medullary thyroid ca?
parafollicular C cells
which thyroid cancers respond to radioactive iodine?
papillary and follicular thyroid ca only
explain bethesda classification for FNA, malignancy risk, and recommendation
1-6, 1 is non-diagnostic (repeat FNA), 2 is benign (0-3% risk), 3 is atypia/follicular cell of undetermined significance (5-15% risk, repeat FNA), 4 follicular neoplasm (15-30%, at least lobectomy), 5 suspicious (60-75%, at least lobectomy), 6 is malignant (at least lobectomy)
most common ectopic location of inferior parathyroid gland
thymus - inferior more likely to be ectopic than superior
indications for parathyroidectomy in primary hyperthyroidism
symptoms of hypercalcemia, asymptomatic with serum Ca > 1 above normal, renal involvement / kidney stones, osteoporosis, age <50
secondary vs tertiary hyperparathyroidism: mechanism? tx?
secondary -> renal failure -> phosphate retention and decreased vitamin D -> hypocalcemia -> hyperparathyroidism, tx w/ Ca supplements, vitamin D, phos binders – in tertiary hyperparathyroidism renal disease corrected w/ transplant however parathyroid glands are hyperplastic and overproduce PTH, tx w/ subtotal (3 1/2 gland) or total parathyroidectomy w/ autoimplantation
increased serum Ca, decreased urine Ca, normal PTH - dx, tx?
familial hypercalcemic hypocalciuria, caused by defect in PTH receptor in distal convoluted tubule of kidney, causes increased reabsorption of Ca; tx nothing
most common site of mets for parathyroid ca?
lung
what is MEN1, which is most common symptom, what do you treat first
MEN1 = PPP; Menin gene, parathyroid hyperplasia (1st symptomatic w/ urinary symptoms), pituitary adenoma (prolactinoma), pancreatic islet cell tumors (gastrinoma, 50% multiple, 50% malignant) correct hyperparathyroidism first
what is MEN2a, which is most common symptom, what do you treat first
MEN2a = PPM; RET protooncogene, parathyroid hyperplasia, pheochromocytoma (often bilateral), medullary Ca of thyroid (diarrhea most common 1st symptom, often bilaterally, #1 cause of death) – need to correct pheochromocytoma first
what is MEN2b, which is most common symptom, what do you treat first
MEN2b = PMM; RET protooncogene; pheochromocytoma, medullary Ca of thyroid (same as MEN2a, 1st symptom diarrhea, often bilateral, MCC of death), mucosal neuromas / Marfan’s habitus
most common cause of hypercalcemia? outpatient? hospital?
most common cause in outpatient setting is hyperparathyroidism, in a hospitalized pt most commonly due to cancer that produce PTHrP (small cell lung ca, breast ca)
mechanism of grave’s disease
IgG antibodies to TSH / thyrotropin receptors
most common cause of primary hyperaldosteronism? tx?
idiopathic bilateral adrenal hyperplasia (60%), tx is medical w/ spironolactone
most important factor in thyroid cancer? how does it affect staging?
age. if age <55, cancer either stage 1 (no distant mets) or stage 2 (distant mets) – lymph node status, tumor size do not matter. for age >55, tumor size, nodes and mets TNM system
most common primary tumor to metastasize to thyroid gland?
renal cell carcinoma»_space;> lung > breast > esophageal
Rate limiting step of catecholamine synthesis?
L tyrosine to L dopa by tyrosine hydroxylase
Hurthle cell vs follicular cell carcinomas?
Hurthle cell <10% of thyroid cancers, subtype of follicular; needs vascular/capsular invasion, eosinophilic cells packed w/ mitochondria derived from oncocytic/xyphilic cells of the thyroid, often multifocal, bilateral, more likely to metastasize to local nodes/distant sites, higher mortality – not effectively treated w/ iodine
spread of follicular cell thyroid ca
hematogenous
indications for post op radioactive iodine following total thyroidectomy?
large tumor >4 cvm, extrathyroidal extension of the tumor regardless of size, LN metastasis, and high risk features (Tall cell / columnar cells)
treatment of hypercalcemic crisis
IV crystalloids, bisphosphonates/calcitonin, dialysis
primary thyroid lymphoma is associated with…
hashimoto thyroiditis
most common ectopic location of superior parathyroid gland
retro/paraesophageal - inferior more likely to be ectopic than superior
Best screening test / highest sensitivity test for pheochromocytomna
PLASMA metanephrines
what is pseudohypoparathyroidism?
inesnsitivity to PTH - characterized by elevated PTH but hypocalcemia and hyperphosphatemia
best test to monitor recurrent disease after total thyroidectomy and post op iodine ablation of follicular ca?
serum thyroglobulin levels, if elevated check 131I scan
malignancy associated with thyroglossal duct cyst
papillary thyroid ca - if discovered incidentally after cyst resection, pt should undergo total thyroidectomy
paramedian or abducted position of vocal cord
recurrent laryngeal nerve injury - paramedian position leads to weak voice, abducted position leads to hoarse voice and ineffective cough
pathophys of familial hypocalciuric hypercalcemia
mutation in CASR (calcium receptor) of parathyroid/kidney, lack of calcium signal increases PTH level, which increases renal calcium reabsorption
most common cause of primary adrenal insufficiency in the US? in the world?
autoimmune adrenal atrophy, worldwide tuberculosis
most common cause of secondary adrenal insufficiency
exogenous glucocorticoid therapy > bilateral adrenal resection > pituitary tumors
most common cause of cushing syndrome? 2nd most common?
exogenous corticosteroid administration > ACTH producing pituitary adenoma
challenges to lap right adrenalectomy (3)
- need to retract liver, 2. need to mobilize duo 3. short/posteriorly located adrenal that drains into IVC, posing risk of injury to IVC
most accurate test for hyperthyroidism?
TSH – should have suppressed/low TSH in hyperthyroid states
direct effects of PTH
acts on bone (stimulates osteclasts, suppress osteoblast), acts on kidney at DCT (inhibits phosphate/bicarb reabsorption) and promote hydroxylation of 25-vitD to 1-25 vitD
what promotes intestinal calcium reabsorption?
1-25 hydroxyvitamin D
what is a “lateral aberrant thyroid”
ectopic thyroid tissue found in neck, typically represents metastatic thyroid cancer within a lymph node, most often its papillary type
what is hungry bone syndrome
prolonged hypocalcemia
