ABSITE Review - Thyroid Flashcards
What is the blood supply to the parathyroid glands?
Inferior thyroid artery from the thyrocervical trunk
What is the venous drainage of the thyroid galnd?
Superior and Middle thyroid veins to IJ vein
Inferior thyroid vein to innominate vein
What are the signs of superior laryngeal nerve injury?
Loss of projection and easy voice fatigability (opera singers)
Where the recurrent laryngeal nerve loops in both sides?
Left RLN loops around aortic arch; Right RLN loops around right subclavian (or innominate artery)
What are the signs of superior laryngeal nerve injury?
Injury results in hoarseness; bilateral injury can obstruct airway –> needs emergency tracheostomy
Which RLN is most likely to be nonrecurrent?
Right RLN 2-3%
What is the function of thyroglobulin?
Store T3 and T4 in colloid
What is the next step for posthyroidectomy stridor?
Open neck and remove hematoma emergently –> can result in airway compromise
What is the Wolff-Chaikoff effect?
Patients given high doses of iodine (Lugol’s solution, potassium iodide), which inhibits TSH action on thyroid and inhibits organic coupling of iodide, resulting in less T3 and T4 release
What is the work up needed for an asymptomatic thyroid nodule?
1st - TSH - if elevated, give thyroxine; if not elevaed, proceed with FNA
What are the possible results and next step of FNA?
Shows follicular cells –> thyroidectomy or lobectomy (5-10% malignancy risk)
Shows thyroid CA –> thyroidectomy or lobectomy
Shows cyst fluid –> drain fluid, if it recurs –> thyroidectomy or lobectomy
Shows colloid tissue –> likely colloid goiter, treat with thyroxine or surgery if it enlarges
Indeterminant (10-25%) –> repeat FNA
T/F: Thyroid nodules are more common in females and 85% are benign.
TRUE
What is the MCC of goiter?
Iodine deficiency
What is the usual finding and treatment for a thyroglossal duct cyst?
Classically moves upward with swallowing
Tx - need to take midportion or all of the hyoid bone along with the cyst
What are the two drugs used for hyperthyroidism treatment?
PTU and methimazole
What is the MOA and side effects of PTU?
MOA - Inhibits peroxidases and prevents DIT and MIT coupling
SEs - aplastic anemia or agranulocytosis (rare)
What is the MOA and side effects of methimazole?
MOA - Inhibits peroxidases and prevents DIT and MIT coupling
SEs - cretinism in newborns (crosses placenta), aplastic anemia or agranulocytosis (rare)”
When is more safe to do a thyroidectomy in a pregnant patient?
2nd trimester
What is the MCC of hyperthyroidism and symptoms?
Graves’ disease
Sxs - exophthalmos, pretibial edema, atrial fibrillation, heart dysfunction, heat intolerance, thirst, increase appetite, weight loss, sweating, palpitations
What is the cause of Graves’ disease?
Caused by IgG antibodies to TSH receptor
What is the preop preparation needed for Graves’ disease?
PTU or methimazole until euthyroid, beta-blocker, 1 week before surgery, Lugol’s solution for 10-15 days to decrease friability and vascularity (start only after euthyroid)
What is the MCC of hypothyroidism in adults?
Hashimoto’s disease
What is the cause of Hashimoto’s thyroiditis?
Both humeral and cell-mediated autoimmune disease (microsomal and thyroglobulin antibodies)
What is ssen in pathology in Hashimoto’s thyroiditis?
Lymphocytic infiltrate
What are the usual symptoms and diagnostic findings of De Quervain’s thyroiditis?
Viral URI, tender thyroid, sore throat, mass, weakness, fatigue
Elevated ESR
What is Riedel’s fibrous struma and what it is associated with?
Woody, fibrous component that can involve adjacent strap muscles and carotid sheath
Can resemble thyroid cancer or lymphoma (need biopsy)
Associated with sclerosing cholangitis, fibrotic diseases, retroperitoneal fibrosis
What facts are worrisome for thyroid malignancy?
Solid, solitary, cold, slow growing, hard, male, age >50, previous neck XRT, MEN IIa or IIb
What is the MC thyroid cancer? What is the main risk factor?
Papillary thyroid carcinoma (80-90%)
Risk Factors - childhood radiation, older age (worst prognosis)
The papillary thyroid cancer spreads to …
lymphatics
What are the pathologic findings of papillary thyroid cancer?
Psammoma bodies (calcium) and Orphan Annie nuclei
When is radioactive iodine needed after surgery?
Metastatic disease, residual local disease, positive lymph nodes or capsular invasion
What is important about thyroid replacement and radioactive iodine therapy?
Do not give thyroid replacement until after treatment because it will suppress uptake
How the follicular thyroid cancer spreads? Where it goes most commonly?
Hematogenously - most commonly to bone.
Which cancer is most aggressive - Follicular or Papillary?
Follicular
Which syndrome is medullary thyroid carcinama associated with?
MEN IIA & IIB
From which cells, the medullary thyroid carcinama arises from?
Parafollicular cells
What is seen in the pathology of medullary thyroid carcinoma?
Amyloid deposition
What is the treatment of choice for medullary thyroid cancer?
Total Thyroidectomy and central neck dissection
When is a prophylactic thyroidectomy needed?
Prophylactic thyroidectomy and central node dissection in MEN Iia or Iib patients at age 2
What is the most aggressive thyroid cancer?
Anaplastic thyroid carcinoma, rapidly lethal
When is the best time for radioactive iodine therapy?
4-6 weeks after thyroidectomy - TSH levels are th highest
