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93 terms

Endocrinology

Pasha Otolaryngology
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embryologic origin thyroid
endoderm between 1st and 2nd branchial arch on floor of pharynx (foramen cecum) invaginates 4th week and descends into mesenchymal tissue
embryologic pathology
athyreosis (rare), ectopic thyroid, thyroglossal duct cyst
inferior and superior parathyroid arteries usually arise from this
inferior thyroid artery (superior parathyroid artery may arise from superior thyroid artery)
blood supply to thyroid isthmus (and where it comes from)
aortic arch or innominate artery -> thyroid ima artery
lymphatic drainage of isthmus and medial lateral lobes
" " of inferior lateral lobes
delphian (prelaryngeal) and digastric
pretracheal and cervical nodes
SLN internal branch parallels __ and then goes through ___. may form ___ __ ___
superior thyroid artery
thyrohyoid membrane
loop of Galen (after anastomosing with sensory branch of RLN)
SLN external branch innervates
cricothyroid muscle
RLN relationship to inferior thyroid artery
near middle 1/3 of gland it crosses posteriorly or superficially to the inferior thyroid artery
describe thyroid hormone synthesis
thyroglobulin is iodinated to form MIT, DIT (mono/di iodotyrosine) which link to form triiodothyronine T3 or thyroxine T4
this is 90% of thyroid output
T4
what is thyroid hormone transported on (protein and %)
TBG thyroxine binding globulin 75%
thyroxine binding pre albumin TBPA 15%
albumin 5%
these organs convert T4 to T3 and rT3 via 5'monodeiodinase
liver, kidneys, muscle
T3 is __ x more active than T4 and binds with higher affinity to TBG
4
propylthiouracil and methimazole belong to this class
thioamides
mechanism of thioamides
blocks conversion of T4 and oxidation and organification of iodine
Wolf-Chaikoff Effect
excess iodine inhibitis thyroid hormone synthesis
this test is more specific for hypo/hyper thyroidism
free T4
this test is most sensitive for hypo/hyperthyroidism
TSH
what does RT3U (resin T3 uptake) measure
binding capacity of existing TBG, increased RT3U suggests decreased total TBG
TBG, total T4, RT3U, free T4 in normal patients
normal, normal, normal, normal
TBG, total T4, RT3U, free T4 in pregnant patients
increased, increased, decreased, normal
TBG, total T4, RT3U, free T4 in liver/renal disease
decreased, decreased, increased, normal
TBG, total T4, RT3U, free T4 in hyperthyroidism
normal, increased, increased, increased
TBG, total T4, RT3U, free T4 in hypothyroidism
normal, decreased, decreased, decreased
false negative rate of FNA
1-10%
this FNA finding suggests nodular or adenomatous goiter
uniform follicular epithelium and abundant colloid
these 2 types of finding may be benign or carcinoma, requires hemithyroidectomy to examine architecture
follicular cells, hurthle cells
hurthle cells associated with this condition
Hashimoto's thyroiditis
99mTc pertechnetate is trapped by these cells
follicular cells
this tracer used to evaluate for metastasis and also for ablation for hyperthyroidism and residual disease
131Iodine
this tracer is expensive, must be delivered daily, testing requires 2 visits at 4 and 24 hrs (shorter half life)
124 Iodine
malignancy rate for hypofunctioning/cold nodule
5-20%
malignancy rate for hyperfunctioning or autonomous functioning "hot" nodule
4%
which staging system to use for papillary/follicular/medually thyroid cancer depends on this criteria
< or > 45yo
papillary/follicular/medually thyroid cancer staging <45yo
stage I - any T, N, M0
stage II - any T, N, M1
T staging for papillary/follicular/medually thyroid cancer
T1 - <2cm
T2 - >2cm, <4cm
T3 - >4cm, minimal extrathyroidal extension
T4
4a - beyond thyroid capsule
4b - prevertebral fascia, carotid, mediastinal vessels
N staging for papillary/follicular/medually thyroid cancer
N0 - no nodes
N1a - delphian or pre/paratracheal LNs
N1b - cervical, superior mediastinal nodes
Staging for papillary/follicular/medually thyroid cancer >45yo
I - T1, N0, M0
II - T1-2, N0, M0
III - T1-3, N0-1a, M0
IVa - T1-4a, N0-1b, M0
IVb - T1-4b, N0-1b, M0
IVc - T1-4b, N0-1b, M1
T staging for anaplastic thyroid cancer
T4a - intrathyroidal/surgically resectable
T4b - extrathyroidal/surgically unresectable
Staging for anaplastic thyroid cancer
IVa - T4a, any N, M0
IVb - T4b, any N, M0
IVc - T4b, any N, M1
thyroid neoplasia - high risk criteria
AMES
age (>41yo men, >51yo women)
metastases
extrathyroidal, major capsular involvement
size (>5cm)
single most significant overall indicator of poor prognosis
distant mets, especially to bone
most common type of benign adenoma
follicular adenoma
most common thyroid cancer and %
papillary, 70-80%
this syndrome is a risk factor for papillary thyroid cancer (PTC)
Gardner's syndrome
histopath for PTC
psamomma bodies (calcific)
Orphan Annie eyes (intranuclear vacuoles)
multicentric
unencapsulated neoplastic cells (ground glass appearance) with fibrovascular stalks
improvement in survival with elective neck dissection in PTC?
no
neck management in PTC?
modified neck dissection for palpable nodes only
may consider lobectomy and isthmusectomy in these patients with PTC
<1cm in younger patients, controversial
follow up in this amount of time for RAI after thyroidectomy for PTC
6 weeks
second most common thyroid cancer and %
follicular carcinoma (FTC), 10%
20-50% of FTC have this type of spread
hematogenous spread with distant metastasis (lymphatic spread rare)
histopath for FTC
unifocal
malignancy differentiated by presence of extracapsular spread, invasion of lymphatics or vasculartor or metastasis
solid, trabecular, or follicular growth patterns
5 year survival for PTC, FTC and FTC with distant mets, and hurthle cell tumor (oncocytic carcinoma)
95% for PTC
70-85% for FTC (20% with distant mets)
50% for hurthle cell (oncocytic carcinoma)
do Hurthle cell tumors take up radioactive iodine?
no, less sensitive to thyroid suppression and diagnostic and therapeutic radioactive iodine therapy
2 types of medullary thyroid cancer (MTC), their prevalence (%), centricity, laterality, which one is worse prognosis
familial (20-25%), multifocal, bilateral
sporadic (70-75%), unifocal, unilateral, worse prognosis
medullary thyroid cancer derived from this cell type
neuroendocrine parafollicular or C-cells (produce calcitonin)
mutation and chromosome for MTC
Ret-3 oncogene, chromosome 10
management for MTC
total thyroidectomy, elective modified neck dissection, medical thyroid suppression therapy
consider this in childhood with positive germline RET mutations
prophylactic thyroidectomy
prognosis for anaplastic carcinoma including median survival
uniformly fatal (2-6 month median)
histopath of anaplastic carcinoma
bizarre cells
giant and spindle cell variation with high mitotic activity, large areas of necrosis, significant infiltration
primary lymphomas of the thyroid are most commonly this type of tumor
non Hodgkin B cell tumors
primary lymphoma of the thyroid associated with these conditions
chronic lymphocytic thyroiditis, Hashimoto's thyoiditis
MEN I, II (2a), III (2b)
MEN I (Werner's) - PPP pituitary adenoma, pancreatic tumors, parathyroid hyperplasia
MEN II (Sipple's) - MPP medullary thyroid cancer, pheochromocytoma, parathyroid hyperplasia
MEN III (2b) - MPMM medullary thyroid cancer, pheochromocytoma, mucosal neuromas, marfanoid habitus
may consider prior to thyroidectomy to reduce vascularity of gland
Lugol's solution (potassium iodine)
indications for thyroidectomy
suspicion of malignancy
mediastinal extension
compression symptoms (airway compromise, dysphagia)
cosmesis
failed medical management Grave's or hyperthyroidism
pregnancy in Grave's or Hashimoto's thyroiditis
documented metastasis from thyroid carcinoma
Rx for respiratory distress from postop hematoma
immediately remove sutures and open wound
mortality rate from thyroid storm
20-50%
Rx thyroid storm
inorganic iodine
PTU (propylthiouracil)
propranolol
corticosteroids
supportive measures (glucose containing IVF, cooling blanket, O2, antipyretics), ICU admission for cardiac monitoring
another name for toxic nodular goiter
Plummer's disease
PPx Grave's disease
thyroid stimulating immunoglobulins (TSIs) stimulate glandular hyperplasia via TSH receptor -> goiter and increased T3, T4 secretion
risks for graves
radiation exposure, women (adolesence or 30-40yo), genetic disposition
SSx grave's
exophthalmos (autoimmune - T cell - retrobulbar fibroblast interaction which has Ag similar to TSH receptor, secrete GAGs, collagen deposition. previously thought to be extraocular muscle deposition)
diffuse goiter, hyperthyroid symptoms, infiltrative dermopathy
these types of thyroiditis can be painful
subacute granulomatous thyroiditis (de Quervain's)
acute suppurative
another name for Hashimoto's thyoiditis
chronic autoimmune
PPx Hashimoto's
antithyroglobulin and antimicrosomal antibodies -> TSH receptor -> transient hyper, then hypothyoidism
Dx Hashimoto's
antithyroid peroxidase (antimicrosomal ABs, anti-TPO, and anti-Tg)
ESR, TFT, FNA for suspicious nodules
thyroid fibrosis of unknown origin, rock hard thyroid, local pressure, hypothyroidism
Riedel's thyroiditis
these parthyroids have a more variable location
inferior (generally 1-2cm from entrance of inferior thyroid artery to lower thyroid pole)
superior paras - 1cm above intersection RLN with inferior thyroid artery
parathyroid embryology
third dorsal branchial pouch ->inferior paras and thymus
fourth dorsal branchial pouch -> superior paras and C-cells of thyroid
embryologic pathology of parathyroids
supernumeray parathyroids
aberrant parathyroids (most commonly at anterior superior mediastinum)
action of parathyroid hormone (PTH)
increases serum calcium, decreases phosphate by stimulating osteoclastic resorption from bone, increasing Ca absorption in kidney, activating 25-hydroxyvitamin D to 1,25 dihydroxyvitamin D, increasing phosphate excretion
causes of hypercalcemia
CHIMPANZEES
Calcium (exogenous)
Hyperparathyroidism
Immobility
Metastases to bone
Paget's disease
Addison's disease
Neoplasia (solid tumors prostate, lung, colon, breast)
Zollinger Ellison (hypergastrinemia)
Endocrine (familial hypocalciuric hypercalcemia, hyperthyroidism, pheochromocytoma)
Exogenous (excess vit A, D, thiazides, lithium, estrogens, milk-alkali syndrome)
Sarcoidosis (also other granulomatous disease TB, berylliosis)
SSx hypercalcemia/hyperparathyroidism
stones, bones, psychiatric overtones
nephrolithiasis, cholelithiasis
osteitis fibrosa cystica
confusion
medical management hypercalcemia
saline diuresis
bisphosphonates
plicamycin
calcitonin
glucocorticoids
gallium
hemodialysis
most common cause of secondary hyperparthyroidism
chronic renal disease
how does thallium technetium subtraction scan work? sensitivity?
thallium taken up by thyroid + paras
technetium taken up by thyroid only
90%
indications for parathyroidectomy
symptomatic hyperaparathyroidism (bone pain, pathologic fractures, ectopic calcifications, intractable itching)
persistently elevated serum calcium
radioguided parathyroidectomy - how it works
tracer injected 1.5-2 hrs prior to surgery, gamma probe to identify abnormal gland
SSx hypoparathyroidism and hypocalcemia
tetany or neuromuscular excitability
Chvostek's sign
Trousseau's sign
DiGeorge embryology
congenital abnormality of third and fourth branchial pouches, agenesis of parathyroid glands, may have athymia
pseudohypoparathyroidism etiology
end organ resistance to effects of PTH