Flashcards in Fiser ABSITE Ch. 22 Thyroid Deck (80):
What is the origin of the thyroid?
1st and 2nd pharyngeal pouches
What is the blood supply of the thyroid with origins?
superior thyroid arter is the 1st branch off the external carotid artery; inferior thyroid artery is off the thyrocervical trunk
What is the blood supply to the parathyroids and how should they be ligated in thyroidectomy?
inferior thyroid arteries, ligate close to thyroid to avoid injuring parathyroids
What is the blood supply to the thyroid isthmus that is occurs in 1% and its origin?
Ima artery arises from the innominate or aorta
What is the venous drainage of the thyroid and where do they drain?
Superior and middle thyroid veins drain into the internal jugular. The inferior vein drains to the innominate vien
Nonrecurrent laryngeal nerve arises directly from the vagus and occurs in 2-3%. Which side is more common?
The superior laryngeal nerve tracks close to what other structure?
superior thyroid artery but is variable
What is the innervation of the cricothyroid muscle and what does injury result in?
superior laryngeal nerve, loss of projection and easy voice fatigability
Where does the recurrent laryngeal nerve track?
runs posterior to thyroid lobes in the tracheosophageal groove. can track with inferior thyroid artery but is variable
What structures do the right and left recurrent laryngeal nerves loop around?
right loops around right subclavian, left loops around aorta
What does the recurrent laryngeal nerve innervate?
motor to all larynx except cricothyroid
Injury to recurrent laryngeal nerve results in hoarseness. What additional tx is need for bilateral injury and why?
needs emergency trach since bilateral injury can obstruct airway
What is the posterior medial suspensory ligament of the thyroid that is close to the RLNs and requires careful dissection?
Ligament of Berry
What is the molecule that stores T3 and T4 in colloid?
What is the most lateral posterior extension of thyroid tissue called? They can be rotated medially to find what structures? (left behind with subtotal thyroidectomy because of proximity).
Tubercles of Zuckerkandl
What is the name of the cells that produce calcitonin?
Parafollicular C cells
What is a long-term side effect of thyroxine treatment?
Postthyroidectomy pt develops stridor. What do you do?
open neck emergently to remove hematoma, can result in airway compromise
Thyroid storm is most common after surgery in pt with undiagnosed ____?
What are the following sx of?:
increased HR, fever, numbness, irritability, vomiting, diarrhea, high-output cardiac failure (most common cause of death)
Describe the Wolf-Chaikoff effect which is very effective for pts in thyroid storm.
Patient 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 first step in dx of asymptomatic thyroid nodule?
thyroid function tests
Asymptomatic thyroid nodule FNA shows cyst fluid. It is drained and it recurs, what next?
thyroidectomy or lobectomy
Asymptomatic thyroid nodule with normal TFTs what is the next step in dx?
Thyroid FNA shows colloid tissue what is the tx?
Low chance of malignancy (
Thyroid FNA shows follicular cells, what next and what is the malignancy rate?
thyroidectomy or lobectomy (5-10% malignancy rate)
What percentage of thyroid nodules are benign?
What next if a thyroid nodule FNA is indeterminate?
Thyroid nodule FNA is indeterminate, radionucleotide study shows hot nodule, what next?
Give thyroxine for 6 months, if size does not decrease perform lobectomy
Thyroid nodule FNA is indeterminate, radionucleotide study shows cold nodule, what next?
thyroidectomy or lobectomy
Diffuse enlargement of thyroid without evidence of functional abnormality = nontoxic colloid goiter. What is the tx?
Tx: try to suppress with thyroxine; 131I (may be ineffective), thioamides, subtotal thyroidectomy or lobectomy on side of goiter if medical treatment ineffective
What is the name of the thyroid lobe that occurs in 10%, extends from the isthmus toward the thymus?
What is the cyst that classically moves upward with swallowing?
thyroglossal duct cyst
What is the tx for thyroglossal duct cyst and why?
Resection, susceptible to infection and my be premalignant. (Also need to take midportion or all of hyoid bone along with the cyst)
What are the two main side effects of PTU and Methimazole?
aplastic anemia or agranulocytosis
What is the treatment for hyperthyroidism that is good for young pts, small goiters and mild T3 and T4 elevation?
PTU and methimazole
What is the treatment for hyperthyroidism that is good for pts who are poor surgical candidates or unresponsive to PTU?
radioactive iodine (131I)
When is the best time to operate in pregnant women with hyperthyroidism?
2 trimester due to decreased risk of teratogenic events and premature labor
What is the most common cause of hyperthyroidism and what is the pathophys?
Graves' disease, IgG antibodies to TSH receptor
What is the recurrence rate for tx of Graves' disease with thioamides, 131I, and subtotal thyroidectomy?
70%, 10%, 10%
Suspicious nodule in pt with Graves' disease, what is the tx?
bilateral subtotal or total thyroidectomy
What is the preop preparation for a pt with Graves' disease undergoing a bilateral subtotal or total thyroidectomoy?
Preop preparation: PTU or methimazole until euthyroid, _-blocker, 1 week before surgery, Lugol's solution for 10-15 days to decrease friability and vascularity (start only after euthyroid)
What is the most common cause of thyroid enlargement?
toxic multinodular goiter
Sx of toxic multinodular goiter include ___; What could precipitate sx?
cardiac symptoms, weight loss, insomnia, airway compromise; contrast dyes
What is the tx for toxic multinodular goiter and single toxic nodule?
131I and thioamides; 131I can be less effective in some (inhomogeneous uptake by gland); subtotal thyroidectomy or lobectomy if medical treatment ineffective
What is the most common cause of hypothyroidism in adults?
Why can a goiter develope in Hashimoto's disease?
lack of organification of trapped iodide inside gland
What usually precipitates DeQuervains's thyroiditis?
What is the tx for De Quervains thyroiditis?
Rare condition of woody, fibrous component to thyroid that can involve adjacent strap muscles and carotid sheath • Can resemble thyroid CA or lymphoma (need biopsy) • Disease frequently results in hypothyroidism and compression. Tx is steroids and thyroxine. May need isthmectomy or trach.
Riedel's fibrous struma
What is the most common endocrine malignancy in the US?
What is the most common type of thyroid CA?
What type of thyroid CA is the least aggressive, slow growing and has the best prognosis?
What is the prognosis in papillary thyroid CA based on?
What type of thyroid cancer's pathology has psammoma bodies and ophan Annie nuclei?
Papillary thyroid CA less than what size can have a lobectomy instead of total thyroidectomy?
Papillary Thyroid CA with clinically positive cervical nodes or extrathyroidal tissue requires what additional tx?
Papillary thyroid CA with metastatic disease, residual local disease, positive lymph nodes or capsular invasion requires what addtional tx?
131I 6 weeks after surgery
When would you give XRT for papillary thyroid CA
unresectable or no response to 131I
What is the 5 year survival in papillary thyroid CA?
Enlarged lateral neck lymph node that shows normal appearing tissue. What is it and what is the tx?
papillary thyroid CA with lymphatic spread, total thyroidectomy and MRND
What percentage of follicular thyroid carcinoma has metastatic disease at the time of presentation?
What is the route of metastasis and most common site with follicular thyroid carcinoma?
If thyroid nodule FNA shows just follicular cells, what is the chance of malignancy?
Lobectomy for follicular cells on thyroid FNA. Pathology shows adenoma or follicular cel hyperplasia. What next?
What size thyroid lesions showing follicular CA need total thyroidectomy?
Follicular thyroid CA with clinically positive cervical nodes or extrathyroidal tissue involvement. What additional tx is needed?
Follicular thyroid CA > 1 cm or extrathyroidal disease need what tx in addition to thyroidectomy?
131I 6 weeks after surgery
What is the 5 year survival rate with follicular thyroid CA?
What does the pathology show in medullary thyroid carcinoma?
What can be used to test for medullary thyroid CA? Causes increase in calcitonin?
From what cells does Medullary thyroid carcinoma arise and what do they secrete?
parafollicular C cells, calcitonin
What two other conditions should be screened for if medullary thyroid carcinoma is diagnosed?
hyperparathyroidism and pheochromocytoma
What are two sx of elevated calcitonin?
flushing and diarrhea
Tx for medullary thyroid carcinoma is total thyroidectomy with what other dissection?
Prophylactic thyroidectomy and central node dissection in MEN IIa or IIb patients at what age?
What can be monitored for disease recurrence in medullary thyroid carcinoma?
What is the 5 year survival in medullary thyroid carcinoma?
What is the 5 year survival for anaplastic thyroid cancer?