CHAPTER 22- THYROID.txt

1st and 2nd pharyngeal pouches

• 1) released from the hypothalamus
• 2) acts on the anterior pituitary gland and causes release of TSH

• 1) released from the anterior pituitary gland
• 2) acts on the thyroid gland to release T3 + T4 (through a mechanism that involves cAMP)
• 3) TRF + TSH release are controlled by T3 and T4 through a negative feedback loop

1st branch off external carotid artery

• 1) off thyrocervical trunk
• 2) supplies inferior and superior parathyroids
• 3) ligate close to the thyroid to avoid injury to parathyroid glands with thyroidectomy

occurs in 1%, arises from the innominate or aorta and goes to the isthmus

drain into internal jugular vein

drains into the innominate vein

1) in 2-3%, more common on the right

• 1) motor to cricothyroid muscle
• 2) runs lateral to thyroid lobes
• 3) tracks close to superior thyroid artery but is variable
• 4) injury results in loss of projection and easy voice fatigability (opera singers)

• 1) motor to all of the larynx except the cricothyroid muscle
• 2) runs posterior to thyroid lobes in the tracheoesophageal groove
• 3) can track with the inferior thyroid artery but are variable
• 4) left RLN loops around aorta; right RLN loops around right subclavian (or innominate) artery
• 5) injury results in hoarseness, bilateral injury can obstruct airway --> needs emergency tracheostomy
• 6) the right nerve is more likely not to be recurrent compared with the left
• 7) risk of injury for nonrecurrent laryngeal nerve injury during thyroid surgery

posterior medial suspensory ligament close to RLNs; careful dissection

• 1) stores T3 and T4 in colloid
• 2) plasma T4:T3 ratio is 15:1; T3 more active form (is tyrosine + iodine)
• 3) most T3 produced in periphery by T4 to T3 conversion by peroxidases

Peroxidases link (or seperate) tyrosine and iodine

• 1) thyroid hormone transport
• 2) T3 +T4 also bind albumin

TSH

• 1) most lateral, posterior extension of thyroid tissue
• 2) rotate medially to find RLNs
• 3) this portion is left behind with subtotal thyroidectomy because of proximity to RLNs

produce calcitonin

• 1) measures free T3 by having it bind resin
• 2) increased resin uptake --> hyperthyroidism or decreased TBG
• 3) decreased resin uptake --> hypothyroidism or increased TBG

• 1) TSH levels should fall to 50%
• 2) osteoporosis is a long term side effect

open neck and remove hematoma emergently--> can result in airway compromise

• 1) Symptoms:
• 1- increased HR
• 2- fever
• 3- numbness
• 4- irritability
• 5- vomiting
• 6- diarrhea
• 7- high output cardiac failure (most common cause of death)

• 2) most common after surgery in patient with undiagnosed Graves Disease
• 3) can also be precipitated by:
• 1- anxiety
• 2- adrenergic stimulants
• 3- excessive palpation of the gland
• 4) Tx:
• 1- beta-blockers
• 2- PTU
• 3- lugol's solution (KI)
• 4- cooling blankets, oxygen, glucose,fluid
• - emergent thyroidectomy rarely indicated

• 1) very effective for patients in thyroid storm
• 2) 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 + T4 release

• 1st- Thyroid function tests
• 1-if elevated, give thyroxine; nodule should regress within 6 months
• 2- if not elevated, proceed with fine-needle aspiration (FNA)

• 2nd- FNA
• A) Determinant in 75-90%--> follow appropriate treatment
• 1- shows follicular cells--> thyroidectomy or lobectomy (5-10% malignancy risk)
• 2- shows thyroid Ca--> thyroidectomy or lobectomy and appropriate treatment
• 3- shows cyst fluid --> drain fluid (if recurs, thyroidectomy/lobectomy)
• 4- shows colloid tissue--> most likely colloid goiter; low chance of malignancy (<1%); tx: thyroxine, thyroidectomy/lobectomy if enlarges)

• B) Indeterminant in 10-25% --> get radionuclide study
• 1- hot nodule--> thyroxine for 6 months; if size does not decrease, perform lobectomy
• 2- cold nodule-->
• 1) thyroidectomy or lobectomy (more likely malignant than hot nodule)
• 2) 85% of thyroid nodules are bengin
• 3) thyroid nodules have female predominance

• 1) any abnormal enlargement
• 2) most identifiable cause is iodine deficiency
• 3) Tx: iodine replacement
• 4) diffuse enlargement without evidence of functional abnormality= nontoxic colloid goiter
• 1- tx: try to suppress with thyroxine, ¹³¹I (may be ineffective), thioamides, subtotal thyroidectomy, or lobectomy on side of goiter if medical treatment ineffective

• 1) usually secondary (vessels originate from superior and inferior thyroid arteries
• 2) primary substernal goiter- rare (vessels originate from innominate artery)
• 1- Tx: try to suppress with thyroxine, ¹³¹I (may be ineffective), thioamides, subtotal thyroidectomy/lobectomy on each side of goiter if medical treatment ineffective

most likely from acquired disease with inferior extensions of a normally placed gland

Pyramidal lobe- occurs in 10%, extends from isthmus toward the thymus

• Lingual thyroid:
• 1) thyroid tissue that persists in the area of the foramen cecum at the base of the tongue
• 2) symptoms: dysphagia, dyspnea, dysphonia
• 3) 2% malignancy risk
• 4) Tx: thyroxin suppression; abolish with ¹³¹I or resection if it is enlarged or suggestive of cancer, or if it does not shrink after medical therapy
• 5) is the only thyroid tissue in 70% of patients who have it

• Thyroglossal duct cyst
• 1) classically moves upward with swallowing
• 2) susceptible to infection and may be premalignant
• 3) Tx: resection--> need to take midportion or all of hyoid bone along with the thyroglossal duct cyst

• 1) Good for:
• 1- young patients
• 2- small goiters
• 3- mild T3/T4 elevation

• PTU (thioamides)
• 1- Inhibits peroxidases and prevents DIT and MIT coupling
• 2- Side effects: aplastic anemia or agranulocytosis (rare)

• Methimazole
• 1- inhibits peroxidases and prevents DIT and MIT coupling
• 2- side effects: cretinism in newborns (crosses placenta) and aplastic anemia or agranulocystosis

• 1) good for patients who are poor surgical risks or unresponsibe to PTU
• 2) Radioactive iodine should not be used in children or during pregnancy--> can traverse the placenta

• Good for:
• 1- large glands
• 2- cold nodules in toxic glands
• 3- toxic multinodular goiters not responsive to medical therapy
• 4- toxic adenomas not responsive to medical therapy
• 5- pregnant patients not controlled with medical therapy

2) Best time to operate is 2nd trimester (decreased risk of teratogenic events and premature labor)

3) subtotal thyroidectomy can leave patient euthyroid

• 1) toxic diffuse goiter
• 2) Associated with:
• 1- women
• 2- expothalmos
• 3- pretibial edema
• 4- atrial fibrillation
• 5- heart dysfunction
• 6- heat intolerance
• 7- thirst
• 8- increased appetite
• 9- weight loss
• 10- sweating + palpitations
• 2) Graves is the most common cause of hyperthyroidism (80%)
• 3) caused by IgG antibodies to TSH receptor (long-acting thyroid stimulator, thyroid-stimulating immunoglobulin)
• 4) if large, can get cervical compression syndromes
• 5) Dx:
• 1- high ¹²³I uptake (thyroid scan) diffusely in thyrotoxic patient with goiter
• 2- LATS level
• 3- decreased TSH
• 4- increased T3/T4
• 6) Tx:
• 1- thioamides (70% recurrence)
• 2- ¹³¹I (10% recurrence)
• 3- subtotal thyroidectomy (10% recurrence)
• 4- total thyroidectomy with thyroxine replacement if medical therapy fails
• 7) medical therapy usually manages hyperthyroidism
• 8) Unusual to have to operate on these patients unless in setting of suspicious nodule
• 9) preop preperation:
• 1- PTU or methimazole until euthyroid
• 2- beta-blocker
• 3- 1 week before surgery, lugol's solution for 10-15 days to decrease friability and vascularity (start only after euthyroid).
• 10) Operation: bilateral subtotal or total thyroidectomy
• 11) Indications for surgery:
• 1- noncompliant patient
• 2- recurrence after medical therapy
• 3- children
• 4- pregnant women not controlled with medical therapy
• 5- concomitant suspicious thyroid nodule

• 1) most common cause of thyroid enlargement
• 2) women, age >50 years, normal thyroid function tests
• 3) Symptoms:
• 1- cardiac symptoms
• 2- weight loss
• 3- insomnia
• 4- airway compromise
• 5- symptoms can be precipitated by contrast dyes
• 4) usually nontoxic 1st
• 5) caused by hyperplasia secondary to chronic low-grade TSH stimulation
• 6) Tx:
• 1- ¹³¹I and thoamides; ¹³¹I can be less effective in some (inhomogenous uptake by gland)
• 2- subtotal thyroidectomy if medical treatment ineffective
• 3- unusual to have to operate on these patients unless in setting of suspicious nodule

• 1) women; younger, can cause cervical compression
• 2) >3 cm usually symptomatic
• 3) Dx: thyroid scan
• 4) 20% of hot nodules eventually cause symptoms
• 5) thought to function autonomously
• 6) Tx:
• 1- ¹³¹I and thioamides
• 2- lobectomy if medical treatment ineffective

• 1) trophoblastic tumors
• 2) TSH-secreting pituitary tumors

• 1) most common cause of hypothyroidism in adults
• 2) Enlarged gland, painless, chronic thyroiditis
• 3) Women; history of childhood XRT
• 4) can cause thyrotoxicosis in the acute early stage
• 5) caused by both humeral and cell-mediated autoimmune disease (microsomal and thyroglobulin antibodies)
• 6) Goiter secondary to lack of organification of trapped iodide inside gland
• 7) pathology shows lymphocytic infiltrate
• 8) Tx: thyroxine 1st line; partial thyroidectomy if continues to grow despite thyroxine, if nodules appear, or compression symptoms occur
• 9) frequently no surgery is necessary for Hashimoto's disease

• 1) usually secondary to contiguous spread
• 2) normal thyroid function tests, fever, dysphagia, tenderness
• 3) upper respiratory tract infection (URI) symptoms most common precursor (staph/strep)
• 4)Tx: antibiotics
• 1- may need lobectomy to rule out cancer in patients with unilateral swelling and tenderness
• 2- may need thyroidectomy for persistent inflammation

• 1) can be associated with hyperthyroidism initially
• 2) Viral URI, tender thyroid, sore throat, mass, weakness, fatigue
• 3) more common in women
• 4) elevated ESR
• 5) Tx: steroids + ASA
• 1- may need lobectomy to rule out cancer in patients with unilateral swelling and tenderness
• 2- may need total thyroidectomy for persistent inflammation

• 1) woody, fibrous component that can involve adjacent strap muscles and carotid sheath
• 2) can resemble thyroid cancer or lymphoma (need biopsy)
• 3) disease frequently results in hypothyroism and compression symptoms
• 4) associated with:
• 1- sclerosing cholangitis
• 2- fibrotic diseases
• 3- methysergide treatment
• 4- retroperitoneal fibrosis
• 5)Tx:
• 1- steroids and thyroxine
• 2- may need isthmectomy or tracheostomy
• 3- if resection needed, watch for RLNs

• 1) most common endocrine malignancy in the United States
• 2) Follicular cells on FNA
• 1- 5-10% chance of malignancy (unable to differentiate between follicular cell adenoma, follicular cell hyperplasia, normal thyroid tissue, andd follicular cell Ca on FNA)
• 3) Worrisome for malignancy:
• 1- solid
• 2- solitary
• 3- cold
• 4- slow growing
• 5- hard
• 6- male
• 7- age >50
• 8- previous neck XRT
• 9- MEN IIa or IIb
• 4) sudden growth- could be hemorrhage into previously undetected nodule or malignancy
• 5) patients can also present with voice changes and dysphagia

need to be differentiated from carcinomas--> require lobectomy

• 1) colloid, embryonal, fetal--> no increase in cancer risk
• 2) still need lobectomy to prove it is adenoma

• 1) most common (80-90%) thyroid Ca
• 2) least aggressive, slow growing, has the best prognosis
• 3) young adults, women, children
• 4) Risk factors: childhood XRT (very inc. risk)--> most common tumor following neck XRT
• 5) older age (>45-50) predicts a worse prognosis
• 6) lymphatic spread 1st, but is not prognostic
• 7) prognosis is based on local invasion
• 8) rare metastases- lung most common
• 9) Children are more likely to be node positive (70-80%) than are adults (10-20%)
• 10) large, firm nodules in children are worrisome
• 11) many are multicentric
• 12) pathology- psammoma bodies (calcium) and orphan annie nuclei
• 13) Treatment:
• 1- minimal/incidental (<1cm)--> lobectomy
• 2- Total thyroidectomy for:
• 1- bilateral lesions
• 2- multicentricity
• 3- history of XRT
• 4- positive margins
• 5- tumors >1cm
• 3) clinically positive cervical nodes- need ipsilateral MRND
• 4) Extrathyroidal tissue involvement- need ipsilateral MRND
• 5) ¹³¹I 6 weeks after surgery when:
• 1- metastatic disease
• 2- residual local disease
• 3- positive lymph nodes
• 4- capsular invasion
• 6) XRT only for unresectable disease not responsive to ¹³¹I
• 7) do not give thyroid replacement until after treatment with ¹³¹I--> will suppress uptake
• 8) 95% 5-year survival rate; death secondary to local disease
• 9) enlarged lateral neck lymph node that shows normal appearing thyroid tisse is papillary thyroid Ca with lymphatic spread.
• Tx: total thyroidectomy and MRND

• 1) hematogenous spread (bone most common)--> 50% have metastatic disease at the time of presentation
• 2) more aggressive than thyroid papillary cell cancer
• 3) older adults (50-60s), women
• 4) FNA shows just follicular cells- 10% chance of malignancy; need thyroidectomy
• 5) Tx:
• 1- lobectomy--> if pathology shows adenoma or follicular cell hyperplasia nothing else needed
• 2- If follicular Ca- total thyroidectomy for lesions >1cm or extrathyroidal disease
• 3- clinically positive cervical nodes- need ipsilateral MRND
• 4- extrathyroidal tissue involvement- need ipsilateral MRND
• 5- patients with lesions >1cm or extrathyroidal disease (or capsular invasion)- ¹³¹I 6 weeks after surgery
• 6- if microinvasive (<1cm), has rare nodal spread (<10%), and is usually incidental finding on pathology--> as long as margins are negative, lobectomy is probably all that is needed
• 7- 70% 5-year survival rate; prognosis based on stage

• 1) can be associated with MEN IIa or IIb
• 2) usually the 1st manifestation of MEN IIa and IIb
• 3) tumor arises from parafollicular C cells (which secrete calcitonin)
• 4) C-cell hyperplasia is considered premalignant
• 5) pathology- shows amyloid deposition
• 6) gastrin can be used to test for medullary thyroid Ca--> causes increase in calcitonin
• 7) calcitonin- can cause flushing and diarrhea
• 8) need to screen for hyperparathyroidism and pheochromocytoma
• 9) lymphatic spread- most have involved nodes at time of diagnosis
• 10) early metastases to lung, liver, and bone
• 11) Tx:
• 1- total thyroidectomy with central node dissection
• 2- MRND if patient has clnically positive nodes (bilateral MRND if both lobes have tumor) or extrathyroidal disease present
• 3- prophylactic thyroidectomy and central node dissection in MEN IIa or IIb patients at age 2
• 4- liver and bone metastases prevent attempt at cure
• 5- XRT may be useful for unresectable local and distant metastatic disease
• 6- may be useful to monitor calcitonin levels for disease recurrence
• 7- more aggressive than follicular and papillary Ca
• 8- 50% 5-year survival rate; prognosis based on presence of regional and distant metastases

• 1) most are benign (hurthle cell adenoma); presents in older patients
• 2) early nodal spread if malignant
• 3) metastases go to bone and lung
• 4) Tx: total thyroidectomy; MRND for clinically positive nodes

• 1) elderly patients with long-standing goiters
• 2) most aggressive thyroid cancer
• 3) rapidly lethal (0% 5 yr survival rate); usually beyond surgical management by diagnosis
• 4) Tx: total thyroidectomy for the rare lesion that can be resected
• 5) can peform palliative thyroidectomy for compressive symptoms or give palliative chemotherapy or XRT

• 1) papillary
• 2) follicular
• 3) medullary
• 4) Hurthle cell

• 1) papillary and follicular thyroid Ca only
• 2) can cure bone and lung metastases
• 3) done 6 weeks after surgery

• 1) recurrent thyroid papillary or follicular Ca
• 2) primary inoperable tumors due to local invasion
• 3) papillary thyroid Ca with extrathyroidal disease
• 4) follicular thyroid Ca >1cm or with extrathyroidal disease
• 5) patients with papillary of follicular cell Ca with metatstases--> need to perform total thyroidectomy to facilitate uptake of ¹³¹I to the metastatic lesions

• 1) sialoadentitis
• 2) GI symptoms
• 3) infertility
• 4) bone marrow suppression
• 5) parathyroid dysfunction
• 6) leukemia

TSH level highest 4-6 weeks after thyroidectomy- best time for ¹³¹I scan for metastatic disease

Thyroxine can help suppress TSH and slow metastatic disease. Its administered only after ¹³¹I therapy has finished.

• 1) lymphoma
• 2) squamous cell carcinoma