ABSITE REVIEWABSITE REVIEWThyroid/ParathyroidThyroid/Parathyroid

David Grossman M.D.

12/4/06

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

• Low T3 concentrations

What percentage of T3 is derived from T4

• 80%

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

• Papillary

What is the major thyroid hormone binding protein

• Thyronine binding globulin (TBG)

What percentage of T4 and T3 are bound?

• Greater than 99.5%

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

What factors decrease TSH secretion?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

Mechanism of action of PTU

• Prevents DIT, MIT coupling

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

• Blocks conversion of T4-T3

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

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

What lab abnormality is associated with DeQuervain’s thyroiditis?

• Elevated ESR• Can be associated with hyperthyroidism• PE/symptoms: Tender thyroid, sore throat,

mass, weakness, fatigue• Treat with steroids/ASA

What genetic mutation is associated with medullary thyroid cancer?

• Ret proto oncongene

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

• FNA

Can radioactive iodine be safely given during pregnancy?

• No

True or False: Cardiac output is decreased in hypothyroidism

• True

What are the hemodynamics of a thyroid storm?

• Tachychardia• Increased Cardiac output• Decreased SVR

What muscle is not innervated by the recurrent laryngeal nerve?

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

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

• Inferior thyroid arteries

What bone finding is pathognomonic finding for hyperparathyroidism?

• Osteitis fibrosa cystica

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

• False: Solitary parathyroid adenoma is the most common etiology

What are the 4 opthalmologic signs of hyperthyroidism?

• Exopthalmos• Lid lag• Lid retraction• Periorbital swelling

What is the initial treatment of thyroid storm?

• IV fluids• Propranalol• PTU• Iodine• Hyothermia

What are the CNS manifestations of myxedema?

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

Why is the pulse pressure wide in patients with thyrotoxicosis?

• Increased blood flow and vasodilation

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

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

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

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

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

• Hoarseness

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

• The tracheoesophageal groove

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

• I31-I radioablation

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

Follicular carcinoma metastases occur primarily by what route?

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

How is the pathologic diagnosis of follicular thyroid carcinoma confirmed?

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

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

• True

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

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

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

• Loss of high pitched voice

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

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

• False

Which thyroid cancer has the best prognosis?

• Papillary

Which thyroid cancer is associated with MEN II

• Medullary

Which thyroid cancer is associated with psammoma bodies?

• Papillary

FNA of nodule reveals amyloidosis. Which thyroid cancer?

• Medullary thyroid carcinoma

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

• 70%

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

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

What are the components of MEN I syndrome?

• Parathyroid hyperplasia• Islet cell neoplasms• Pituitary tumors

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

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

Where is calcitonin produced?

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

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

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

What is the treatment of anaplastic thyroid cancer?

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

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

• Total thyroidectomy by age 5

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

• Prophylactic total thyroidectomy by age 2

Hyperparathyroidism is associated with what gene?

• Prad

What is the treatment of Hypercalcemic Crisis?

• Fluids, furosemide, dialysis

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

What is the treatment for parathyroid Cancer?

• Wide en bloc excision and ipsiltateral thyroidectomy

• Recurrence about 50%• Most common location for metastasis:

LUNG

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

• FNA

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

• Age

What is the Cl to phos ratio in Hyperparathyroidism?

• Cl/Phos ratio is > 33

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

What is the Wolff-Chaikoff effect?

• High Iodine doses inhibits TSH

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

• Aplastic anemia• Do not use in pregnancy-crosses the

placenta- causes cretinism