ABSITE REVIEW Thyroid/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? 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
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
False: Solitary parathyroid adenoma is the most common etiology 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
Loss of high pitched voice 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%
Calcium 9-11, normal PTH, low urinary Ca 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
Re-opening of cervical wound 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
Parathyroid adencarcinoma 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
Most common location for the missing gland is normal anatomic position 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