EN Pathologies

Question 1

differentiate between thyrotoxicosis and hyperthyroidism

Answer 1

thyrotoxicosis - elevated T3/T4 in blood
hyperthyroidism - overactive thyroid gland leading to excessive release of thyroid hormone

Question 2

expected TSH and T3/T4 in patients with thyrotoxicosis

Answer 2

low TSH, high T3/T4

Question 3

what are some causes of thyrotoxicosis

Answer 3

• Graves’
• toxic multi-nodular goiter
• single autonomous toxic nodule
• subacute thyroiditis

Question 4

what is the role of thyroid uptake results when a patient presents with thyrotoxicosis?

Answer 4

differential diagnosis - low TSH, high T3/T4
dose calculation dependent on RAIU

Question 5

increase or decrease %RAIU
iodinated IV contrast

what can be done about it?

Answer 5

decrease
wait 1-2 mos

Question 6

increase or decrease %RAIU
oil based iodinated contrast

what can be done about it?

Answer 6

decrease
wait 3-6 mos

Question 7

increase or decrease %RAIU
Cytomel

what can be done about it?

Answer 7

decrease
wait 2-3 weeks

Question 8

increase or decrease %RAIU
Synthroid

what can be done about it?

Answer 8

decrease
wait 4-6 weeks

Question 9

increase or decrease %RAIU
PTU

what can be done about it?

Answer 9

decrease
wait 3-5 days

Question 10

increase or decrease %RAIU
Methimazole

what can be done about it?

Answer 10

decrease
wait 5-7 days

Question 11

increase or decrease %RAIU
iodinated food, supplements, vitamins, cough syrups, antiseptic

what can be done about it?

Answer 11

decrease
wait 2-4 weeks

Question 12

increase or decrease %RAIU
amiodarone

what can be done about it?

Answer 12

decrease
wait 3-6 mos

Question 13

increase or decrease %RAIU
SSKI, Lugol’s

what can be done about it?

Answer 13

decrease
wait 2-4 weeks

Question 14

increase or decrease %RAIU
Perchlorate

what can be done about it?

Answer 14

decrease
wait 1 week

Question 15

increase or decrease %RAIU
ectopic tissues, well-differentiated thyroid ca, struma ovarii

Answer 15

decrease

Question 16

increase or decrease %RAIU
renal failure/congestive heart failure

Answer 16

decrease

Question 17

increase or decrease %RAIU
Lithium

Answer 17

increases

Question 18

increase or decrease %RAIU
Exogenous TSH

Answer 18

increases

Question 19

increase or decrease %RAIU
abrupt withdrawal of anti-thyroid medication

Answer 19

increase

Question 20

increase or decrease %RAIU
hypoalbuminemia

Answer 20

increase

Question 21

increase or decrease %RAIU
iodine depletion

Answer 21

increase

Question 22

what is a DISCORDANT nodule?

Answer 22

hot with Tc, but cold with iodine
due to being able to trap but not organify

Question 23

what are ectopic thyroid tissues?

Answer 23

thyroid tissue found outside typical thyroid bed location

Question 24

where are ectopic thyroid tissues usually found?

Answer 24

sublingual, thoracic, supraovarian

Question 25

characteristics of a primary hyperparathyroid

Answer 25

• increased PTH and Ca2+
• commonly caused by adenoma

Question 26

characteristics of a secondary hyperparathyroid

Answer 26

• caused by hypocalcemia (secondary to renal disease or vit D deficiency)

Question 27

characteristics of a tertiary hyperparathyroid

Answer 27

hypercalcemia and high PTH

Question 28

difference between appearance of adenoma vs. hyperplasia and ectopic glands on a parathyroid scan.

Answer 28

adenoma - single focus more visible on delayed
hyperplasia - more than one increased focus on delayed
ectopic glands - in neck or mediastinum

Question 29

what can cause false positives on parathyroid scans?

Answer 29

• MIBI concentrated by thyroid adenomas/carcinomas
• hold up of activity in subclavian vein

Question 30

what can cause false negatives on parathyroid scans?

Answer 30

• lower sensitivity for detection of hyperplasia and second adenomas
• rapid washout
• failure to image mediastinum
• small adenomas