EN Pathologies Flashcards
differentiate between thyrotoxicosis and hyperthyroidism
thyrotoxicosis - elevated T3/T4 in blood
hyperthyroidism - overactive thyroid gland leading to excessive release of thyroid hormone
expected TSH and T3/T4 in patients with thyrotoxicosis
low TSH, high T3/T4
what are some causes of thyrotoxicosis
- Graves’
- toxic multi-nodular goiter
- single autonomous toxic nodule
- subacute thyroiditis
what is the role of thyroid uptake results when a patient presents with thyrotoxicosis?
differential diagnosis - low TSH, high T3/T4
dose calculation dependent on RAIU
increase or decrease %RAIU
iodinated IV contrast
what can be done about it?
decrease
wait 1-2 mos
increase or decrease %RAIU
oil based iodinated contrast
what can be done about it?
decrease
wait 3-6 mos
increase or decrease %RAIU
Cytomel
what can be done about it?
decrease
wait 2-3 weeks
increase or decrease %RAIU
Synthroid
what can be done about it?
decrease
wait 4-6 weeks
increase or decrease %RAIU
PTU
what can be done about it?
decrease
wait 3-5 days
increase or decrease %RAIU
Methimazole
what can be done about it?
decrease
wait 5-7 days
increase or decrease %RAIU
iodinated food, supplements, vitamins, cough syrups, antiseptic
what can be done about it?
decrease
wait 2-4 weeks
increase or decrease %RAIU
amiodarone
what can be done about it?
decrease
wait 3-6 mos
increase or decrease %RAIU
SSKI, Lugol’s
what can be done about it?
decrease
wait 2-4 weeks
increase or decrease %RAIU
Perchlorate
what can be done about it?
decrease
wait 1 week
increase or decrease %RAIU
ectopic tissues, well-differentiated thyroid ca, struma ovarii
decrease
increase or decrease %RAIU
renal failure/congestive heart failure
decrease
increase or decrease %RAIU
Lithium
increases
increase or decrease %RAIU
Exogenous TSH
increases
increase or decrease %RAIU
abrupt withdrawal of anti-thyroid medication
increase
increase or decrease %RAIU
hypoalbuminemia
increase
increase or decrease %RAIU
iodine depletion
increase
what is a DISCORDANT nodule?
hot with Tc, but cold with iodine
due to being able to trap but not organify
what are ectopic thyroid tissues?
thyroid tissue found outside typical thyroid bed location
where are ectopic thyroid tissues usually found?
sublingual, thoracic, supraovarian
characteristics of a primary hyperparathyroid
- increased PTH and Ca2+
- commonly caused by adenoma
characteristics of a secondary hyperparathyroid
- caused by hypocalcemia (secondary to renal disease or vit D deficiency)
characteristics of a tertiary hyperparathyroid
hypercalcemia and high PTH
difference between appearance of adenoma vs. hyperplasia and ectopic glands on a parathyroid scan.
adenoma - single focus more visible on delayed
hyperplasia - more than one increased focus on delayed
ectopic glands - in neck or mediastinum
what can cause false positives on parathyroid scans?
- MIBI concentrated by thyroid adenomas/carcinomas
- hold up of activity in subclavian vein
what can cause false negatives on parathyroid scans?
- lower sensitivity for detection of hyperplasia and second adenomas
- rapid washout
- failure to image mediastinum
- small adenomas
