Endocrine GW Flashcards
Thyroid hormones
T3 triiodothyronine
T4 tetraiodothyronine
What cells trap iodide in thyroid
Thyroid follicular cells trap iodide through the iodide pump
Iodide is oxidized to form 1 of 2 molecules
MIT or DIT
One MIT and one DIT molecule =
T3
One DIT and one DIT molecule =
T4
What does the anterior pituitary gland produce and secrete
TSH - thyroid stimulating hormone
Hypothalamus produces and secretes what hormone
TRF - thyrotropin releasing factor
Which RP can be used for but is not recommended for routine imaging
I131
Indications for thyroid imaging
Relate gland structure to function
Evaluate size and nodules/masses
Identify ectopic tissue
Thyroid RPs and doses
pertechnetate 2-10 mCi (imaging)
I123 0.1-0.2 (uptake)
- 0.2-0.6 (imaging)
I131 0.004-0.01 (uptake)
- 0.05 - 0.2 (imaging)
Administration to imaging time for each RP for thyroid
Pertechnetate 15-30 minutes
I123 3-4 or 16-24 hours
I131 6-24 hours
How long may a low iodine diet be recommended prior
3-10 days prior
How to magnify views with pinhole collimator
Bring collimator closer to neck
Most interfering drugs and procedures must be withheld
2-4 weeks
Thyroxine (thyroid med) 4-6 weeks
Antithyroid meds 2-8 days
Which lobe of thyroid is larger
Right
Nonfunctioning “cold” nodules means
Cancer
Cyst
Hematoma
Inflammatory conditions
Benign adenoma
Hot nodules mean
Typically benign
Thyroid uptake at 2-6 hours reflects what function
Iodide trapping and organification