Download Thyroid, Parathyroid, and Adrenal

arises as an outpouching of the primitive foregut
around the third week of gestation
 originates at the base of the tongue at the foramen
cecum
 During its descent, the anlage remains connected to
the foramen cecum via an epithelial-lined tube known
as the thyroglossal duct
 paired lateral anlages originate from the fourth
branchial pouch and fuse with the median anlage at
approximately the fifth week of gestation. The lateral
anlages are neuroectodermal in origin
(ultimobranchial bodies) and provide the calcitonin
producing parafollicular or C cells
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Thyroglossal Duct Cyst and Sinus
 may occur anywhere along the migratory path of the thyroid
 80% are found in juxtaposition to the hyoid bone
 usually asymptomatic but occasionally become infected by oral
bacteria, prompting the patient to seek medical advice
 midline neck mass that moves upward with protrusion of the tongue.
 Sistrunk = which consists of en bloc cystectomy and excision of the
central hyoid bone
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Lingual Thyroid
 failure of the median thyroid anlage to descend normally
 Intervention necessary for obstructive symptoms such as choking,
dysphagia, airway obstruction, or hemorrhage
 Surgical excision rarely needed  should be preceded by an
evaluation of normal thyroid tissue in the neck to avoid inadvertently
rendering the patient hypothyroid.
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TSH is only necessary test
Thyrotropin-Releasing Hormone to evaluate
pituitary function
Thyroid antibodies
Radionuclide Imaging
Ultrasound
CT or MRI scans
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Diffuse Toxic Goiter (Graves' Disease)
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Antibodies against TSH receptor
MCC of hyperthyroidism in US
Strong familial predisposition
Conditions such as the postpartum state, iodine excess, lithium therapy, and bacterial and
viral infections have been suggested as possible triggers
Sx: palpitations, nervousness, fatigue, emotional lability, hyperkinesis, GI complaints
Suppressed TSH with elevated T3, T4
Tx: antithryroid drugs, radioactive idoine, ablation, surgery when others fail or
contraindicated or suspicious nodule
Toxic Multinodular Goiter
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often have a prior history of a nontoxic multinodular goiter
thyroid nodules become autonomous to cause hyperthyroidism.
See suppressed TSH level and elevated free T4 or T3 levels
RAI uptake also is increased, showing multiple nodules with increased uptake and suppression
of the remaining gland.
Subtotal thyroidectomy is the gold standard
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Hyperthyroidism accompanied by fever, central
nervous system agitation or depression,
cardiovascular dysfunction
Beta blockers
 reduce peripheral T4 to T3 conversion
 decrease the hyperthyroid symptoms.
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Oxygen supplementation and hemodynamic support
Lugol's iodine
 decrease iodine uptake and thyroid hormone secretion.
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PTU blocks the formation of new thyroid hormone
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= Suppurative Thyroiditis
Infectious agents can seed it from the
 hematogenous or lymphatic route
 via direct spread from persistent pyriform sinus fistulae or
thyroglossal duct cysts
 penetrating trauma to the thyroid gland
 due to immunosuppression.
Streptococcus and anaerobes account for about 70% of
cases;
 Acute suppurative thyroiditis is more common in children
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 preceded by an upper respiratory tract infection or otitis media
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Treatment consists of IV antibiotics and drainage of
abscesses.
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Painful or painless forms
Painful thyroiditis thought to be viral in origin
Thyroiditis most commonly occurs in 30- to 40year-old women
History of a preceding upper respiratory tract
infection often can be elicited.
In the early stages of the disease, TSH is
decreased, and T4 , and T3 levels are elevated
due to the release of preformed thyroid
hormone from destroyed follicles.
Painless thyroiditis is considered to be
autoimmune in origin
The most common inflammatory disorder of the thyroid and the
leading cause of hypothyroidism.
 Hashimoto's thyroiditis = autoimmune process that
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 activation of CD4+ T (helper) lymphocytes with specificity for thyroid
antigens
 T cells can recruit cytotoxic CD8+ T cells to the thyroid
 autoantibodies, which lead to complement fixation and killing by
natural killer cells
More common in women between the ages of 30 and 50 years old.
An elevated TSH and the presence of thyroid autoantibodies
FNAB is indicated in patients who present with a solitary
suspicious nodule or a rapidly enlarging goiter.
 Treatment
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 Thyroid hormone replacement therapy is indicated in overtly
hypothyroid patients, with a goal of maintaining normal TSH levels.
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replacement of all or part of the thyroid parenchyma
by fibrous tissue
etiology of this disorder is controversial
predominantly in women between the ages of 30 to
60 years old
presents as a painless, hard anterior neck mass, which
progresses over weeks to years to produce symptoms
of compression, including dysphagia, dyspnea,
choking, and hoarseness.
Patients may present with symptoms of
hypothyroidism and hypoparathyroidism as the gland
is replaced by fibrous tissue
Surgery is mainstay of treatment
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4% of individuals in the United States
Assess symptoms
Determine family history
 risk factor for the development of both medullary
and nonmedullary thyroid cancer
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Do PE
 best palpated from behind the patient and with
the neck in mild extension.
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Then proceed to further tests…
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80% of all thyroid malignancies
predominant thyroid cancer in children and individuals exposed to
external radiation.
Lymph node metastases are common,
Orphan Annie nuclei
Psammoma bodies
Excellent prognosis with a >95% 10-year survival rate.
AGES scoring system
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Age,
histologic Grade,
Extrathyroidal invasion
metastases and tumor Size
Low versus High risk patients
If any high-risk factors  total or near-total thyroidectomy.
If minimal papillary thyroid carcinoma in removed for other reasons,
unilateral thyroid lobectomy and isthmusectomy is usually enough
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10% of thyroid cancers
Limitations inherent to FNAB diagnosis
Usually are solitary lesions, and the majority are
surrounded by a capsule.
 Treatment
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 Thyroid lobectomy because at least 80% of these
patients will have benign adenomas.
 Intraoperative frozen-section examination usually is
not helpful
 Total thyroidectomy should be performed when
thyroid cancer is diagnosed
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Stop T4 therapy for 4-6 weeks
Radioactive Iodine Scan  look for hot spot
Adjuvant treatment with radioactive iodine
Then resume thyroid replacement therapy,
will help supress
Can follow thyroglobulin measurement as
marker
Screening ultrasound periodically to evaluate
central and lateral neck compartments
5% of thyroid malignancies and arises from the parafollicular or C
cells of the thyroid,
 25% occur within the spectrum of several inherited syndromes
such as familial MTC, MEN2A, and MEN2B.
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 germline mutations in the RET proto-oncogene.
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Present with neck mass, lymphadenopathy in 15-20%
Hematogenous spread
Unilateral if sporadic, multifocal if familial
Amyloid on slides
Screen for MEN!
 Treat pheochromocytoma first
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Total thyroidectomy with bilateral central neck dissection
Followup  measure calcitonin and cEA
10 yr survival 80%
Perform prophylactic thyroidectomy for MEN2 with RET
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1 % of thyroid malignancies in US
Women more common
Classic: long standing neck mass that rapidly enlarges and
becomes painful
Sx: dysphonia, dysphagia, and dyspnea
May be fixed to surrounding structures or may be ulcerated with
areas of necrosis
Confirmed by FNA
Isthmusectomy with or without a tracheostomy may be needed to
alleviate tracheal obstruction.
Treatment and Prognosis
 most aggressive thyroid malignancy
 few patients surviving 6 months
 Combined radiation and chemotherapy in patients with resectable
disease has been associated with prolonged
Superior glands from the fourth branchial pouch (also
thyroid gland)
 Inferior glands form third branchial pouch (also thymus)
 The position of normal superior parathyroid glands is
more consistent
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 with 80% of these glands being found near the posterior aspect
of the upper and middle thyroid lobes,
Approximately 15% of inferior glands are found in the
thymus.
 Undescended inferior glands may be found
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 near the skull base,
 angle of the mandible,
 frequency of intrathyroidal glands is about 2%.
Rely on a G-protein coupled membrane receptor to regulate PTH secretion by
sensing extracellular calcium levels
 PTH secretion also stimulated by low levels of 1,25-dihydroxy vitamin D,
catecholamines, and hypomagnesemia.
 Secreted PTH has a half-life of 2 to 4 minutes.
 PTH functions to regulate calcium levels via its actions on three target organs:
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Bone
Kidney
Gut
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inhibits osteoclast-mediated bone resorption.
Calcitonin produced by thyroid C cells  antihypercalcemic hormone
Vitamin D refers to vitamin D2 and vitamin D3 ,
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both produced by photolysis of naturally occurring sterol precursors
Vitamin D is metabolized in the liver to its primary circulating form, 25-hydroxyvitamin D.
Further hydroxylation  1,25-dihydroxy vitamin D  most metabolically active
Vitamin D stimulates the absorption of calcium and phosphate from the gut and the
resorption of calcium from the bone.
Most cases of PHPT are sporadic.
Occurs within the spectrum of a number o inherited disorders such
as MEN1, MEN2A, isolated familial HPT
 Hyperplasia, Adenoma, Carcinoma
 PHPT is the earliest and most common manifestation of MEN1
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 80 to 100% of patients by age 40 years old
Sx: kidney stones, painful bones, abdominal groans, psychic
moans, and fatigue overtones
 More likely to be asymptomatic and picked up on blood tests
 Measure PTH to decide between the 2 causes of hypercalcemia
 Surgery for complications, classic symptoms, age < 50
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 Total versus focused
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Localization studies: ultrasound, Sestamibi scan
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1% of PHPT cases.
Suspect by preoperatively by the presence of
severe symptoms
 serum calcium levels >14 mg/dL
 significantly elevated PTH levels (5 x normal)
 palpable parathyroid gland
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Local invasion is most common
Treatment
 bilateral neck exploration, with en bloc excision of the
tumor and the ipsilateral thyroid lobe.
 Modified radical neck dissection if lymphadeonopathy
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Uncontrolled PTH secretion,
worsened by polyuria, dehydration, and
reduced kidney function
Treatment consists of therapies to lower
serum calcium levels followed by surgery
The mainstay of therapy involves rehydration
diuresis with furosemide
Further bisphosphonates, etc
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Asymptomatic Patient
 Serum Ca > 1 mg/dl Above upper limits of normal
 Life threatening hypercalcemic episode
 Reduced creatinine clearance
 Renal stones on xray
 Markedley elevated 24 hour urine Ca
 Substantially decreased bone mineral density
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commonly occurs in patients with chronic renal failure but also
may occur in those with hypocalcemia secondary to inadequate
calcium or vitamin D intake, or malabsorption.
The pathophysiology related to hyperphosphatemia, deficiency of
1,25-dihydroxy vitamin D due to loss of renal tissue, low calcium
intake, decreased calcium absorption, and abnormal parathyroid
cell response
generally hypocalcemic or normocalcemic.
treated medically with a low-phosphate diet, phosphate binders,
adequate intake of calcium and 1,25-dihydroxy vitamin D and a
high calcium, low-aluminum dialysis bath.
Surgery if:
 bone pain, pruritus, calcium >11 mg/dL with markedly elevated PTH,
calciphylaxis
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A bilateral neck exploration is indicated
Consider subtotal resection with autotransplant
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some patients develop autonomous
parathyroid gland function and tertiary HPT
after renal transplant
pathologic fractures, bone pain, renal stones,
mental status changes.
Surgery if persists 1 year after transplant
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Hypocalcemia
Vocal cord paralysis
Hypoparathyroidism
Permanent if > 6 mths
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Outer cortex and an inner medulla
The cortex originates from mesodermal tissue
near the gonads
Ectopic adrenocortical tissue may be found in
the ovaries, spermatic cord, and testes.
Adrenal medulla is ectodermal in origin and
arises from the neural crest.
Most extra-adrenal neural tissue regresses but
may persist at several sites.
 The largest of these ia left of the aortic bifurcation
near the inferior mesenteric artery origin and is
designated as the organ of Zuckerkandl.
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Secondary causes from stimulation of the renin-angiotensin system from renal artery stenosis
and to low-flow states such as congestive heart failure and cirrhosis.
Primary hyperaldosteronism results from autonomous aldosterone secretion which, I
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leads to suppression of renin secretion.
1% of hypertension cases.
Hypokalemia
Causes:
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Adenoma 70%
Hyperplasia 30%
Carcinoma rare
Sx: hypertension difficult to control despite multiple-drug therapy, muscle weakness, polydipsia,
polyuria, nocturia, headaches, and fatigue.
Labs: K+. Measure renin-aldosterone
CT scan can localize with sensitivity of 90%
Selective venous sampling
Txs:
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spironolactone (aldosterone antagonist)
amiloride (a potassium-sparing diuretic that blocks sodium channels in the distal nephron
nifedipine
Captopril
Unilateral tumors producing aldosterone are best managed by adrenalectomy
Hypercortisolism
Most common cause iatrogenic
70% are pituitary tumor, 20% adrenal tumor, 10% ectopic ACTH producing tumor
Sx: wt gain, buffalo hump, central obesity, striae, acne, hypertension, neurologic
or pyschiatric disorders
 elevated glucocorticoid levels that are not suppressible by exogenous hormone
administration and loss of diurnal variation
 overnight low-dose dexamethasone suppression test. In this test
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Cushing's syndrome patients do not suppress
Measure ACTH to determine if ACTH dependent;
If ACTH dependent do high dose dexamethoasone test; if no supression then likely ectopic
Laparoscopic adrenalectomy is the treatment of choice for patients with adrenal
adenomas.
 Open adrenalectomy for large tumors (≥6 cm) or those suspected to be
adrenocortical cancers
 Cushing disease treatment is transsphenoidal excision
 May need mineralocorticoid and glucocorticoid replacement therapy
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Deficiencies or complete absence of enzymes involved in adrenal
steroidogenesis.
21-Hydroxylase deficiency is the most common enzymatic defect (>90%
of cases)
 overproduction of adrenal androgens and corticosteroid precursors such as 17-
hydroxyprogesterone and androstenedione.
 converted to testosterone in the peripheral tissues, thereby leading to
virilization.
 Complete deficiency of 21-hydroxylase presents at birth with: virilization,
diarrhea, hypovolemia, hyponatremia, hyperkalemia, and hyperpigmentation.
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Dx: karyotype and measurement of plasma and urinary steroids
Tx: traditionally have been managed medically with cortisol and
mineralocorticoid replacement to suppress the hypothalamic-pituitaryadrenal axis.
teroids required often are supraphysiologic  lead to iatrogenic
hypercortisolism  lap adrenalectomy gaining momentum
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Disorders of the Adrenal Medulla; paraganglioma if extra adrenal
10 percent tumor because
 10% are bilateral, 10% are malignant, 10% occur in pediatric patients,
10% are extra-adrenal, and 10% are familial.
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Pheochromocytomas occur in families with MEN2A and MEN2B
Sx: Headache, palpitations, and diaphoresis
Dx: 24 hr urine for catecholamines and plasma metanephrines
CT to localize tumor
Need alpha blocker first, titrate to orthostatic hypotension
Adrenalectomy is treatment of choice
12-29% are malignant, and these tumors are associated with
decreased
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May be primary, resulting from adrenal disease, or secondary, due
to a deficiency of ACTH
The most commonly encountered causes of primary adrenal
insufficiency are autoimmune disease, infections, and metastatic
deposits.
fulminant meningococcal septicemia (Waterhouse-Friderichsen
syndrome).
Bilateral adrenal hemorrhage also can occur secondary to trauma,
severe stress, infection, and coagulopathies and, if unrecognized,
is lethal.
Suspect in stressed patients with any of the relevant risk factors
laboratory findings: hyponatremia, hyperkalemia, fasting or
reactive hypoglycemia
ACTH stim test
 Peak cortisol levels <20 g/dL suggest adrenal insufficiency
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Replace glucocorticoids and mineralocorticoids
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Postoperative hemodynamic instability
 pheochromocytomas
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Nelson's syndrome from progressive growth
 increased ACTH levels
 hyperpigmentation,
 extraocular muscle palsies.
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You are seeing a postop total
parathyroidectomy patient who complains of
SOB. What do you do?
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A patient is diagnosed with medullary thyroid
cancer, what should you do prior to surgery?
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An FNA shows follicular cells, what should
you recommend
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What are the complications of thyroidectomy
or parathyroidectomy?
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How do your prepare a pheochromocytoma
patient for surgery?