Thyroid Flashcards
What is the incidence of false positives with FNA of thyroid nodules
0.04
What % of the normal population will have a positive Chvostek’s sign
0.1
What is the mean age of presentation of MTC in patients with MEN Ila
27
What % of patients with Hurtle cell carcinoma present with distant metastases
???
The local recurrence rate is higher after subtotal than after total thyroidectomy. True.
???
What % of thyroid nodules are malignant
What % of thyroid cancers are well-differentiated
>90%.
What level of TSH is optimal during suppression therapy
0.1 - 0.5 miU/L.
What is the incidence of permanent recurrent laryngeal nerve injury after total thyroidectomy
1 - 4%.
What % of nodules diagnosed as having follicular or Hurtle cells, are malignant
10- 20%.
What % of the population has more than 4 parathyroid glands
10%.
What % of cases of primary hyperparathyroidism are due to diffuse hyperplasia
14-16%.
What is the average lag time between radiation exposure and development of thyroid cancer
15 - 25 years.
What is the incidence of permanent hypoparathyroidism after total thyroidectomy
1-5%.
What % of malignant nodules are suppressible by exogenous TSH
16%.
What % of nodules with an indeterminate FNA are malignant
16.7%.
What % of cold, warm/cool, and hot nodules are malignant
17%, 13%, and 4%, respectively.
In a non-acute setting, what is the maximum useful amount of calcium supplementation
2 grams of calcium/day.
What % of parathyroid glands are located in the mediastinum
2%.
What % of a parathyroid gland is composed of fat
20-30%.
What % of benign nodules are suppressible by exogenous TSH
21 %.
What % of FNAs of thyroid nodules are either nondiagnostic or suspicious
27%.
What % of cases of primary hyperparathyroidism are due to carcinoma
3%.
What % of the population has only 3 parathyroid glands
3%.
What % of thyroid nodules are malignant in patients with a history of radiation exposure
30 - 50%.
What is the optimal TSH value prior to radioiodine therapy
30 mU/L.
What % of patients have had well-differentiated cancer before developing anaplastic thyroid cancer
47%.
What is the false-negative rate of the RET analysis
5%.
What % of solitary thyroid nodules in children are malignant
50%.
What % of MTCs secrete CEA
50%.
What % of patients have had benign thyroid disease before developing anaplastic cancer
53%.
After ablation therapy, how often are repeat scans performed
6 - 12 months after ablation, then every 2 years.
What % of MTC occurs sporadically
70 - 80%.
What percentage of patients with papillary carcinoma (greater than 1 em) are found to have multicentric disease on pathologic examination of the entire thyroid
70 to 80%.
What study should be performed prior to re-operation for persistent or recurrent hyperparathyroidism
99Tc sestamibi is 85% sensitive in experienced centers; more accurate is patient is placed on cytomel to suppress the thyroid.
What infectious diseases can cause chronic thyroiditis
Actinomycosis, TB, and syphilis.
What are the indications for parathyroid exploration in patients with asymptomatic or minimally symptomatic hyperparathyroidism
Age less than 50. Serum calcium I mg/ml above the upper limits of normal for the lab. Creatinine clearance reduced by 30°/o or more compared with age-matched normal persons. 24-hour urinary calcium excretion >400mg. T -score at lumbar spine, hip, or distal radius
What factor best correlates with the presence of lymph node metastases in papillary carcinoma
Age.
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 their surgery.
What is another cause of bone disease in patients with renal failure that should be ruled out prior to parathyroidectomy
Aluminum bone disease.
Which cardiovascular medication will interfere with radioiodine scanning
Amiodarone.
What antibodies are specific for Hashimoto’s thyroiditis
Antimicrosomal and antithyroglobulin.
What test should be ordered in a patient with an elevated TSH
Antimicrosomal antibody (antithyroperoxidase level) to rule out Hashimoto’s thyroiditis.
What are the characteristics of familial MTC
Autosomal dominant inheritance pattern; not associated with any other endocrinopathies.
What laboratory workup is necessary in patients with MTC
Basal and pentagastrin stimulated calcitonin levels, serum calcium, 24-hour urine catecholamines, VMA, and metanephrine, +/ CEA.
Which of these is lethal prenatally
Blomstrand’s chondrodystrophy.
What are the indications for parathyroidectomy in patients with secondary hyperparathyroidism
Bone pain (most common indication), intractable pruritus, calcium-phosphate product over 70 despite medical treatment, calciphylaxis, and osteitis fibrosa cystica.
What is the most common site of metastasis from follicular thyroid cancer
Bone.
When is prophylactic thyroidectomy recommended in patients with the RET mutation
By age 5 or 6.
How is the definitive diagnosis of follicular thyroid cancer made
By demonstration of capsular invasion at the interface of the tumor and the thyroid gland.
What is the difference in the Ca/Cr clearance ratio in someone with FHH and someone with primary hyperparathyroidism
Ca!Cr clearance 0.02 in primary hyperparathyroidism.
What are the histologic features of papillary thyroid cancer
Calcified laminated bodies called psammoma bodies, elongated, pale nuclei with a ground glass appearance (Orphan Annie-eyes).
What lab test should be obtained in patients with a family history of medullary thyroid cancer
Calcitonin.
What is the appropriate calcium supplementation if the maximum amount of calcium has already been given and the patient is still hypocalcemic
Calcitriol or other vitamin D preparations should be added.
What are the advantages of ultrasound in the evaluation of thyroid nodules
Can detect nodules as small as 2 - 3 mm, can differentiate between solid, cystic, or mixed nodules with >90% accuracy, can detect presence of lymph node enlargement.
What are the disadvantages of ultrasound in the evaluation of thyroid nodules
Cannot accurately distinguish benign from malignant nodules.
What is the best treatment for primary non-Hodgkin ‘s lymphoma of the thyroid gland
Chemoradiation.
Which cell is most commonly proliferated in diffuse parathyroid hyperplasia
Chief cell.
What are the 3 types of cells comprising the parathyroid glands
Chief cells, clear cells, and oxyphil cells.
Which cells produce PTH
Chief cells.
What is the pathophysiology behind secondary hyperparathyroidism from chronic renal failure
Chronic hypocalcemia results from decreased production of 1 ,25(0H)2 vitamin 0 3, bone resistance to PTH, and decreased clearance of PTH and phosphate, resulting in parathyroid hyperplasia and increased levels of PTH.
What is the most common cause of secondary hyperparathyroidism
Chronic renal failure.
What are the indications for calcium supplementation after thyroid or parathyroid surgery
Circumoral paresthesias, anxiety, positive Chvostek’s or Trousseau’s sign, tetany, ECG changes or serum calcium less than 7.1 mild I.
What are the histochemical characteristics of MTC
Congo red dye positive, apple-green birefringence consistent with amyloid; immunohistochemistry positive for cytokeratins, CEA and calcitonin.
What is the significance of elevated preoperative levels of alkaline phosphatase in patients with chronic renal failure undergoing parathyroidectomy
Correlates with a good chance of amelioration of bone pain after parathyroidectomy.
Why is measurement of the C-terminal of PTH not accurate for diagnosis of secondary hyperparathyroidism
C-terminal fragments are cleared by the kidney; elevation may indicate either renal insufficiency or hyperparathyroidism.
What are the histologic features of follicular thyroid cancer
Cuboidal epithelial cells with large nuclei in a well-structured follicular pattern.
What is the appropriate management for a patient with an anaplastic thyroid carcinoma
Debulking and tracheostomy may be performed for palliation of airway obstruction.
What is the most important prognostic indicator of follicular thyroid cancer
Degree of angioinvasion.
What are the CNS manifestations of myxedema
Depression, memory loss, ataxia, frank psychosis, myxedema and coma.
What is the medical management of secondary hyperparathyroidism
Dietary phosphate restriction, phosphate binders, calcium and vitamin D supplementation (calcitriol), sodium bicarbonate (for metabolic acidosis), charcoal hemoperfusion (for pruritus), bisphosphonates.
What is the single most effective chemotherapeutic agent for anaplastic thyroid cancer
Doxorubicin.
How often are serum thyroglobulin levels measured
Every 6 months for the first 3 years, then annually.
During exploration for primary hyperparathyroidism, 3 normal parathyroid glands are found but the fourth cannot be identified. What is the next step in management
Extend the exploration through the existing incision, to include the central neck compartment between the carotids, posteriorly to the vertebral body, superiorly to the level of the pharynx and carotid bulb and inferiorly into the mediastinum.
What is the most common presentation of severe hypercalcemia
Extreme lethargy.
What are the indications for surgical treatment of Graves’ disease
Extremely large glands, presence of a dominant nodule, failure of 1131 , massive enlargement with compressive symptoms, pregnant women intolerant to antithyroid drugs, women of childbearing age and patients who are opposed to radioiodine.
T/F: Follicular cell carcinoma is more aggressive than Hurthle cell
False.
What disease should be ruled out on all patients with h)•percalcemia
Familial benign hypocalciuric hypercalcemia (FHH).
Which of these has the best prognosis
Familial.
What clinical sign is the hallmark of thyroid storm
Fever.
How do patients with Hashimoto’s thyroiditis present
Firm, diffusely enlarged goiter and hypothyroidism.
What is the most common thyroid nodule
Follicular adenoma.
Which thyroid tumors cannot be diagnosed as malignant with FNA
Follicular and Hurthle cell.
What are the 3 types of well-differentiated thyroid malignancies
Follicular, papillary, and Hurthle cell.
Which of these is associated with iodine-deficiency
Follicular.
Which of these is more likely to be seen in a pregnant woman
Follicular.
What are the most common causes of hyperthyroidism
Graves’ disease, toxic multinodular goiter, relapsing thyroiditis, amiodarone-induced thyrotoxicosis, autonomous toxic nodule, subacute thyroiditis, pituitary tumor.
What are the most common causes of hypothyroidism
Hashimoto’s thyroiditis, pituitary tumor, thyroidectomy, and radioactive 1131 treatment for thyrotoxicosis.
A 45-year-old female presents with a 2 year history of diffuse, tender thyroid enlargement, lethargy and a 20-pound weight gain. What is the most likely diagnosis
Hashimoto’s thyroiditis.
What is the most common inflammatory disease of the thyroid
Hashimoto’s thyroiditis.
Most false positives of FNA are due to what disease
Hashimoto’s thyroiditis.
Which of these is relatively unresponsive to ablation with radioactive iodine
Hurthle cell.
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 is the difference in incidence of malignancy between solitary and multiple nodules
Incidence of malignancy in solitary nodules is 5 - 12°/o; incidence is 3°/o in multiple nodules.
Where are the inferior parathyroids typically located
Inferior and anterior to the inferior thyroid artery.
What is the immediate treatment for patients with acute symptomatic hypocalcemia
Intravenous calcium gluconate.
What is the initial treatment of thyroid storm
Intravenous fluids, hypothermia, acetaminophen, propranolol, propylthiouracil (PTU) and iodine.
What is the first line therapy for patients with marked hypercalcemia and/or severe symptoms
Intravenous hydration followed by furosemide.
What is the earliest radiographic lesion seen in osteitis fibrosa cystica
Irregularity of the radial aspect of the second digit middle phalanx
When performing a thyroid resection, where should the inferior thyroid artery be ligated
It should not be ligated. Branches should be ligated individually at the capsule.
What are the 2 types of anaplastic thyroid cancer
Large cell and small cell.
Which is more common
Large cell.
What are the histologic features of Hurthle cell thyroid cancer
Large polygonal thyroid follicular cells with abundant granular cytoplasm and numerous mitochondria.
What medication can be substituted for levothyroxine prior to radioiodine therapy
Liothyronine (Cytomel/T3).
What is the best agent for rapid surgical preparation of thyrotoxic patients
Long acting beta-blocker.
What is the most common thyroid abnormality in hospitalized patients with non-thyroidal illness
Low T3 concentration.
What is the most accurate test for diagnosis of primary hyperparathyroidism
Measurement of intact PTH.
Which of these presents earliest
MEN lib (mean age 19).
Which type of multiple endocrine neoplasia is not associated with hyperparathyroidism
MEN lib.
What is the significance of size with thyroid nodules
More likely to be malignant if>4 em in diameter.
What is the significance of age with thyroid nodules
More likely to be malignant in women over 50 and men over 40 and in both men and women under 20.
What genetic mutation is associated with medullary thyroid cancer
Mutation of the RET proto-oncogene.
What genetic defect results in either Jansen’s chondrodystrophy or Blomstrand’s chondrodystrophy
Mutation of the type I parathyroid hormone receptor.
Which terminal of parathyroid hormone (PTH) is active
N -terminal.
What are the histological features of medullary thyroid carcinoma (MTC)
Nests of small, round cells; amyloid; dense, irregular areas of calcification.
What is the classic bony change associated with hypercalcemia
Osteitis fibrosa cystica; manifested as subperiosteal bone resorption in the phalanges, pelvis, distal clavicles, ribs, femur, mandible, or skull.
Which of these is more likely to be seen in a 30-year-old
Papillary.
Which of these is the most common type of thyroid cancer
Papillary.
Which of these has the best prognosis
Papillary.
Which cells in the thyroid gland secrete calcitonin
Parafollicular or C-cells.
What is the most common cause of primary hyperparathyroidism
Parathyroid adenoma.
What is tertiary hyperparathyroidism
Parathyroid hyperplasia results in autonomous hypersecretion such that hyperparathyroidism continues despite correction of the underlying renal disease.
What other disorders are present in patients with MEN lib
Pheochromocytoma, multiple mucosal neuromas, marfanoid body habitus.
What other disorders are present in patients with MEN Ila
Pheochromocytoma, parathyroid hyperplasia.
When is exogenous T4 used in patients with thyroid carcinoma
Postoperatively in patients with TSH-dependent carcinomas (follicular, papillary, and Hurtle cell).
A 48-year-old male has a serum calcium of 13 mg/dl and a serum PTH of 400 mEq/ml. What is the most likely diagnosis
Primary hyperparathyroidism secondary to a parathyroid adenoma.
What is the most common cause of hypercalcemia
Primary hyperparathyroidism.
A 25-year-old pregnant female, in her 2nd trimester, presents with hyperparathyroidism and a serum calcium of 12 mg/dl. What is the treatment of choice
Prompt parathyroid exploration.
What medications are used for the routine treatment of hyperthyroidism
Propylthiouracil (PTU) and methimazole.
What medication is most commonly used to treat hyperthyroidism during pregnancy
PTU.
What is the treatment of choice for patients with parathyroid carcinoma
Radical resection of the involved gland, the ipsilateral thyroid lobe and the regional lymph nodes.
What is the treatment of choice for patients over 40 with Graves’ disease
Radioactive 1131
What intraoperative modality confirms adequate removal of parathyroid tissue in patients with hyperparathyroidism
Rapid intraoperative PTH assay (expect a decrease of at least 50% ).
How are patients with MTC managed postoperatively
Receive L-thyroxine and 2 weeks of calcium and vitamin D supplementation; serial measurements of calcitonin and CEA.
What thyroid disorder is characterized by replacement of the thyroid gland with fibrous tissue
Reidel’s struma (invasive fibrous thyroiditis, woody thyroiditis).
What enzyme activates vitamin D in the kidney
Renal alpha I - hydroxylase.
A 35-year-old female has a serum calcium of 8.5 mg/dl, a serum PTH of 400 mEq/ml and a serum creatinine of 5.6 mg/dl. What is the most likely diagnosis
Secondary hyperparathyroidism.
What is calciphylaxis
Severe soft tissue calcification that can result in deep nonhealing ulcers and gangrene.
What are the indications for postoperative radioiodine ablation therapy
Significant uptake after a total or near-total thyroidectomy, extrathyroidal uptake, metastatic disease.
Which of these is usually responsive to radiation therapy
Small cell.
In what 4 settings does MTC arise
Sporadic, familial, and in association with multiple endocrine neoplasia Ila or lib.
Which of these has the worst prognosis
Sporadic.
Which of these tends to occur unilaterally
Sporadic.
What are the functions of PTH
Stimulates osteolysis and release of calcium and phosphorus from the bone; increases reabsorption of calcium and magnesium and the excretion of phosphorus and bicarbonate in the kidney; enhances intestinal absorption of calcium by stimulating the activation of vitamin D in the kidney.
What is the treatment of choice for patients with hyperparathyroidism associated with MEN-I or MEN-IIa
Subtotal (3 1/2 gland) parathyroidectomy or total parathyroidectomy with autotransplantation.
What is the surgical treatment of choice for patients with secondary hyperparathyroidism
Subtotal (3 112) parathyroidectomy or total parathyroidectomy with autotransplantation.
Where are the superior parathyroids typically located
Superior and posterior to the inferior thyroid artery and more likely to extend posteriorly and inferiorly or be found retroesophageally.
What are the hemodynamics of thyroid storm
Tachycardia, increased cardiac output and decreased systemic vascular resistance (SVR).
What is the embryologic origin of the thyroid gland
The median downgrowth of the first and second pharyngeal pouches in the area of the foramen cecum.
What is the primary blood supply of the parathyroid glands
The superior and inferior parathyroid arteries, which are usually branches of the inferior thyroid artery.
What test is used to distinguish a hypothalamic defect from a pituitary defect in a patient with hypothyroidism
The TRH stimulation test.
What is the purpose of obtaining a preoperative thyroglobulin level
Thyroglobulin has been shown to correlate well with histologic tumor type and is useful as a marker for tumor recurrence.
What is the appropriate treatment for the above patient
Thyroid hormone replacement therapy.
What is the preferred treatment for patients with toxic multinodular goiter
Thyroid resection (lobectomy to total thyroidectomy) because I 131 treatment often requires repeated doses, does not reduce goiter size and may even cause acute enlargement.
What is the most useful application of thyroid scanning in patients with thyroid cancer
To detect residual thyroid tissue or occult distant metastases after thyroidectomy.
A 44-year-old male presents with a 5 em thyroid nodule. FNA returns fluid, the nodule disappears and the cytology is benign. What is the next step in management
Total thyroid lobectomy with isthmusectomy should be considered because there is an increased chance of malignancy in large cysts.
A 56-year-old male with no risk factors presents with a thyroid nodule. The FNA is nondiagnostic. What is the treatment of choice
Total thyroid lobectomy with isthmusectomy.
A 65-year-old female presents with a cervical lymph node that is found to have well-differentiated thyroid tissue but the thyroid has no palpable abnormality. What is the next step in management
Total thyroidectomy and modified radical neck dissection.
What is the surgical treatment for medullary thyroid carcinoma (MTC)
Total thyroidectomy with central node dissection, lateral cervical lymph node sampling of palpable nodes and a modified radical neck dissection, if positive.
T /F: The incidence of parathyroid adenoma is higher in the presence of a thyroid nodule.
True.
T/F: Microscopic lymph node involvement does not change the long-term survival in patients with papillary thyroid cancer
True.
T/F: All patients with MEN lla will have MTC
True.
T/F: The overall rate of survival is the same after subtotal or total thyroidectomy
True.
T /F: The sensitivity of thyroglobulin testing and radioiodine scans is higher when a patient is off TSH suppression.
True.
T/F: The inferior glands vary in location more than the superior glands
True.
T/F: Thyroglobulin levels should be obtained prior to performing FNA
True; FN A will falsely elevate thyroglobulin levels.
A 36-year-old female presents with a 3 em papillary carcinoma and no clinical evidence of lymph node involvement. She was treated with a total thyroidectomy. What adjuvant therapy is indicated
TSH suppression with thyroid hormone, radioiodine ablation with 1131 , follow-up scan 6 months after ablation with thyroglobulin levels and physical examination.
What is the most sensitive method for detecting thyroid nodules
Ultrasound.
What intraoperative modality may assist in locating an intrathyroidal parathyroid gland
Ultrasound.
What is the most common cause of persistent hyperparathyroidism after parathyroidectomy
Undiscovered or supernumerary parathyroid gland.
What factors significantly increase the risk of sampling error from FNA
Very small (4 em) nodules, hemorrhagic nodules, or multinodular glands.
What is the most reliable method of differentiating a parathyroid adenoma from parathyroid hyperplasia
Visual inspection of all 4 parathyroid glands.
