Thyroid & Parathyroid Flashcards
supplies both the inferior and superior parathyroids
Inferior thyroid artery (off thyrocervical trunk)
Ligate close to thyroid to avoid injury to parathyroid glands with thyroidectomy
Mechanism of TSH
Released from anterior pituitary actso n thyroid to release T3/T4 via increased cAMP
Blood supply to thyroid
Superior thyroid artery (1st branch off external carotid a)
Accessory blood supply to isthmus in 1% of population
Ima artery
Venous drainage of thyroid
Superior/Middle thyroid v: drain into IJ
Inferior thyroid v: drain into innominate v
Injury resulting in loss of projection and easy voice fatigability
Superior largyneal nerve
Supplies motor to the cricothyroid muscles
superior laryngeal n
MC injured n during thyroidectomy
superior laryngeal n
Supplies motor to all larynx except cricothyroid
recurrent laryngeal n
Anatomy of superior vs recurrent laryngeal n
superior: runs lateral to thyroid lobes
recurrent: runs posterior to thyroid lobes in tracheoesophageal groove, left loops around aorta, right loops around innominate
Injury resulting in hoarsness or airway obstruction
rucurrent laryngeal
posterior medial suspensory ligament close to recurrent laryngeal nerves requiring careful dissection
ligament of berry
Plasma T4:T3 ratio
15:1 (T3 is more active form)
T3 production
produced in periphery from T4 to T3 conversion by deiodinases (seperate iodine from tyrosine)
Most common cause of death in thyroid storm
high output cardiac failure
When does thyroid storm occur
after surgery in Graves patient
Treatment of thyroid storm
beta-blockers, Lugol’s solution (KI), cooling blankets, oxygen, glucose
How does Lugol’s solution (KI) work to treat thyroid storm
Wolff-Chaikoff effect - high dose of iodine inhibits TSH action on thyroid, inhibits coupling of iodine results in less T3/T4
FNA: follicular cells
lobectomy
FNA: cyst fluid
drain fluid (unless bloody or recurrent then lobectomy)
FNA: colloid tissue
most likely goiter
Tx w/ thyroxine, lobectomy if enlarging
FNA: normal thyroid tissue + elevated thyroid function tests
solitary toxic nodule
Tx w/ methimazole, iodine if symptomatic
Indeterminant FNA
get radionuclide study,
If Hot: methimazole, iodine
If Cold: lobectomy
Dysphagia, dyspnea, dysphonia
lingual thyroid (base of tongue) tx w/ thyroxine suppression and abolish w/ iodine (only thyroid tissue in most patients who have it
Midline cervical mass between hyoid and thyroid isthmus that moves up w/ swallowing
thyroglossal duct cyst, at risk of infection/premalignant, needs to be resected w/ hyoid bone and thyroglossal duct cyst (Sistrunk procedure)
- Most common location of an ectopic superior parathyroid gland:
tracheoesophageal groove
- Most common location of an ectopic inferior parathyroid gland:
thyrothymic ligament (ie, the thymus)
- Most common location of a missed adenoma if re-operating:
tracheoesophageal groove (“missed” here refers to a reopertion or a scenario where you are the surgeon to whom some other surgeon is referring his or her patient after being unsuccessful)
- Most common location of a parathyroid gland if cannot find it:
normal anatomic position (ie, “continue exploration,” or, if you have meticulously searched, “closed and get a Sestamibi scan” [never do a sternotomy in this scenario!])
* Do not confuse “ectopic” with “missed”
