ABSITE REVIEW Thyroid/Parathyroid

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ABSITE REVIEWThyroid/Parathyroid

• David Grossman M.D.
• 12/4/06

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What is the most common thyroid abnormality in
hospitalized patients with non thyroidal illness?

• Low T3 concentrations

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What percentage of T3 is derived from T4

• 80

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FNA of thyroid. Orphan any cells. What kind of
thyroid cancer?

• Papillary

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What is the major thyroid hormone binding protein

• Thyronine binding globulin (TBG)

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What percentage of T4 and T3 are bound?

• Greater than 99.5

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What is the major cause of a decreased T3
concentration in patients with a critical illness?

• Impaired peripheral conversion of T4 to T3
  secondary to inhibition of the deiodination
  process

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What factors decrease TSH secretion?

• Acute and chronic illness
• Calorie restriction
• Dopamine and dopamine agonists
• Surgical stress
• Minor decreases are associtated with
  carbamazapine, opiates, phenytoin, somatostatin

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Mechanism of action of PTU

• Prevents DIT, MIT coupling

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Mechanism of action of prednisone? ( in terms of
thyroid)

• Blocks conversion of T4-T3

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A patient with a history of radiation exposure as
a child was found to have an enlarged lymph node
on PE. The lymph node is removed and there is
normal appearing thyroid tissue in the lymph
node. What is the diagnosis?

• Papillary Thyroid Cancer

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What is the embryologic origin of the thyroid
gland?

• From median downgrowth of the first and second
  pharyngeal pouches in the area of the foramen
  cecum

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What lab abnormality is associated with
DeQuervains thyroiditis?

• Elevated ESR
• Can be associated with hyperthyroidism
• PE/symptoms Tender thyroid, sore throat, mass,
  weakness, fatigue
• Treat with steroids/ASA

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What genetic mutation is associated with
medullary thyroid cancer?

• Ret proto oncongene

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What is the first test after H and P to evaluate
a thyroid nodule?

• FNA

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Can radioactive iodine be safely given during
pregnancy?

• No

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True or False Cardiac output is decreased in
hypothyroidism

• True

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What are the hemodynamics of a thyroid storm?

• Tachychardia
• Increased Cardiac output
• Decreased SVR

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What muscle is not innervated by the recurrent
laryngeal nerve?

• Cricothyroid
• Cricothyroid is innervated by?
• Superior laryngeal nerve

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All the parathyroids typically receive their
blood supply from what artery?

• Inferior thyroid arteries

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What bone finding is pathognomonic finding for
hyperparathyroidism?

• Osteitis fibrosa cystica

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True or False Hyperparathyroid is most commonly
associated with 4 gland hyperplasia?

• False Solitary parathyroid adenoma is the most
  common etiology

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What are the 4 opthalmologic signs of
hyperthyroidism?

• Exopthalmos
• Lid lag
• Lid retraction
• Periorbital swelling

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What is the initial treatment of thyroid storm?

• IV fluids
• Propranalol
• PTU
• Iodine
• Hyothermia

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What are the CNS manifestations of myxedema?

• Depression
• Memory loss
• Ataxia
• Frank psychosis
• Myxedema
• Coma

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Why is the pulse pressure wide in patients with
thyrotoxicosis?

• Increased blood flow and vasodilation

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Causes of Hypercalcemia

• PTH
• Adrenal insufficiency
• Multiple Myeloma
• Pagets disease
• Sarcoidosis
• Cancer
• Hyperthyroidism/Hypothyroidism
• Milk Alkali
• Immobilization
• D Vitamin D/A excess
• Thiazide Diuretics

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A 45 y/o female presents with a 2 year history of
diffuse, tender thyroid enlargement, lethargy and
20 pound weight gain. What is the most likely
diagnosis?

• Hashimotos thyroiditis
• What is the treatment?
• Thryoid replacement therapy

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What is the appropriate treatment for patients
with thyroglossal duct cysts?

• Excision of the entire cyst, as well as the
  thyroglossal tract to its origin, at the foramen
  cecum, including the central portion of the hyoid
  bone

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What is the venous drainage of the thyroid gland?

• The superior and middle thyroid veins drain into
  the internal jugular vein and the inferior
  thyroid vein drains into the innominate vein

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What is the result of injury to the recurrent
laryngeal nerve?

• Hoarseness

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What is the most common location of the recurrent
laryngeal nerve?

• The tracheoesophageal groove

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What is the definitive, non-surgical treatment of
graves disease?

• I31-I radioablation

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What are the indications for surgical treatment
of Graves disease?

• Extremely large glands, presence of nodules,
  women of childbearing age and patients who are
  opposed to radioiodine

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Follicular carcinoma metastases occur primarily
by what route?

• Hematogenous dissemination to the lungs, bones
  and other peripheral tissues

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How is the pathologic diagnosis of follicular
thyroid carcinoma confirmed?

• Identification of vascular or capsular invasion
  by the tumor from histologic sections

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True or False Exposure to low-dose radiation
therapy is considered a risk factor for thyroid
carcinoma?

• True

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What are the histiochemical characteristics of
medullary thyroid carcinoma

• Congo red dye positive
• Apple-green birefringence consistent with amyloid
• Immunohistochemistry positive for cytokeratins,
  CEA and calcitonin

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What is the embryological origin of the
parathyroid glands?

• The inferior parathyroid glands originate from
  the third pharyngeal pouch
• The Superior parathyroid glands originate from
  the fourth pharyngeal pouch

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What voice problem will a patient have if there
is injury to external branch of superior
laryngeal nerve?

• Loss of high pitched voice

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Recurrent laryngeal nerve supplies all laryngeal
muscles except the cricothyroid which is supplied
by

• Superior laryngeal nerve
• On the right the RLN goes around
• The right subclavean artery
• On the left the RLN goes around the arch of the
  aorta

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True or false The presence of follicular cells
can be used to differentiate between benign and
malignant

• False

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Which thyroid cancer has the best prognosis?

• Papillary

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Which thyroid cancer is associated with MEN II

• Medullary

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Which thyroid cancer is associated with psammoma
bodies?

• Papillary

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FNA of nodule reveals amyloidosis. Which thyroid
cancer?

• Medullary thyroid carcinoma

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What percent of individuals with lingual thyroids
have no other thyroid tissue?

• 70

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What are the lab values in patients with Familial
Hypercalcemic Hypocalciuria?

• Calcium 9-11, normal PTH, low urinary Ca
• Caused by a defect in the PTH receptor in the
  distal convoluted tubule that causes increased
  absorption of Ca
• Treatment nothing, no parathyroidectomy

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Twelve hours after having undergone a subtotal
thyroidectomy, a 30 y/o woman develops agitation
and difficulty breathing. Exam reveals
tachychardia, anterior cervical swelling.
Dressing is dry. The most appropriate treatement
is

• A. insertion of ET tube
• Re-opening of cervical wound
• Determination of the serum Calcium and magnesium
  concentrations
• Administration of morphine
• Administration of oxygen by nasal cannula

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What are the components of MEN I syndrome?

• Parathyroid hyperplasia
• Islet cell neoplasms
• Pituitary tumors

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What is the surgical treatment of choice for
patients with secondary hyperparathyroidism?

• Subtotal (3 and ½) parathyroidectomy or total
  parathyroidectomy with autotransplantation

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Where is calcitonin produced?

• In the parafollicular cells( c-cells) of the
  thyroid

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A patient with MTC has a high urinary VMA and an
enlarged left adrenal gland. What is the next
step in management?

• Medical management with alpha and beta blockers,
  if necessary, followed by resection of the left
  adrenal gland. This should be performed before
  the thyroid surgery

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What are the indications for adjuvant thyroid
hormone in patients with well differentiated
thyroid carcinoma?

• All patients with well differentiated carcinoma
  should be treated with thyroid hormone to
  suppress TSH for life, regardless of the extent
  of surgery

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What is the treatment of anaplastic thyroid
cancer?

• Combination of chemo/radiation
• Adriamycin is best single chemo agent

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MTC associated with MEN IIa. At what age do you
perform thyroidectomy?

• Total thyroidectomy by age 5

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MTC associated with MEN IIb. At what age do you
perform thyroidectomy?

• Prophylactic total thyroidectomy by age 2

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Hyperparathyroidism is associated with what gene?

• Prad

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What is the treatment of Hypercalcemic Crisis?

• Fluids, furosemide, dialysis

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A patient in the hospital is noted to have a very
high calcium and a palpable rock hard neck mass.
What is your diagnosis?

• Parathyroid adencarcinoma

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What is the treatment for parathyroid Cancer?

• Wide en bloc excision and ipsiltateral
  thyroidectomy
• Recurrence about 50
• Most common location for metastasis LUNG

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What is the single most important test in the
diagnostic work-up of a patient with a solitary
thyroid nodule?

• FNA

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What factor best correlates with the presence of
lymph node metastases in papillary carcinoma?

• Age

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What is the Cl to phos ratio in
Hyperparathyroidism?

• Cl/Phos ratio is gt 33

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At reoperation for a missing parathyroid gland,
what is the most common location for the missing
gland?

• Most common location for the missing gland is
  normal anatomic position

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What is the Wolff-Chaikoff effect?

• High Iodine doses inhibits TSH

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What is the major complication (side effect) of
PTU?

• Aplastic anemia
• Do not use in pregnancy-crosses the placenta-
  causes cretinism

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