thyroid

Question 1

Thyroid develops from median outpouching between

Answer 1

1st and 2nd pharyngeal pouch

Question 2

Development and descent dependent on transcription factors: (3)

Answer 2

NKX2.1 and FOXE1 and PAX 8

Question 3

mutations on the transcription factors for thyroid descent are

Answer 3

Mutations can lead to agenesis, dysgenesis or abnormal descent

Question 4

Congenital hypothyroidism ~1 in 3,500 births. Causes variably include abnormal development or loss of function mutations in

Answer 4

enzymes synthesizing thyroid hormones (dyshormonogenesis)

Question 5

Tethered by thyroglossal duct to foramen cecum

obliterates by fetal week

Answer 5

6

Question 6

when the thyroid does not descend as it should, could result in (2)

Answer 6

1. ectopic thyroid tissue along track and beyond

2. thyroglossal duct cysts

Question 7

thyroglossal duct cyst is located _______

Answer 7

midline

Question 8

Thyroid tissue in the abdomen: what’s this!?

Answer 8

struma ovarii (monodermal teratoma)

• can be hyperfunctional and can give rise to carcinoma

Question 9

elevated TSH but no T4/T3. no goiter present…

Answer 9

problem with TSH receptor

since TSH is being made but there is no goiter it means that TSH is not binding to the receptor and causing hypertrophy

Question 10

T354P mutation in the NIS gene

Answer 10

sodium-iodide symporter issue

Question 11

wolf-chaikoff

Answer 11

large amounts of iodine thyroxine secretion leads to down regulation of the NA-I- symporter which restores I concentrations to normal

Question 12

patients present with high TSH in spite of high levels of thyroid hormone due to resistance to thyroid hormone from an abnormal receptor at the level of the pituitary

Answer 12

mutation in thyroid receptor Beta

Question 13

_________________ is the commonest clinically significant congenital thyroid anomaly, ~2-4% of neck masses, most common congenital anomaly of the neck”. Midline, lined by squamous and/or columnar epithelium, ectopic thyroid issue variably present in wall

Answer 13

Thyroglossal duct cyst

Question 14

Entire thyroid can be ectopic such as in

Answer 14

lingual thyroid

Question 15

struma ovarii

Answer 15

ovarian teratomas

Question 16

Thyroid hormones increase the basal metabolic rate by (2)

Answer 16

(1) stimulating futile cycles of protein synthesis and degradation and (2) by increasing the activity of the Na+/K+ exchange