173. Thyroid basic physiology

Question 1

In biochemical thyroid function tests, displays antibodies to TPO

Answer 1

Hashimoto’s thyroiditis

Question 2

Elevated TSH Decreased total or free T4

Answer 2

Hypothyroidism

Question 3

Functional unit of the thyroid

Answer 3

Follicle

Question 4

Low iodine –> low thyroid hormones –> increased TSH –> increased thyroid size

Answer 4

Goiter

Question 5

Elevated TSH Normal total or free T4

Answer 5

Subclinical hypothyroidism

Question 6

GPCR that allows Iodine (I-) to enter the thyroid cells from the blood stream Regulated by TSH

Answer 6

NIS

Question 7

Echo free center on US Smooth back wall Acoustic enhancement

Answer 7

Thyroid cyst

Question 8

Severe mental retardation 2/2 insufficient hormone levels during intrauterine life and infancy

Answer 8

Cretinism (congenital iodine deficiency)

Question 9

Modality of choice for evaluation of thyroid structure No functional information Diagnosis: - nodules - cysts - Hashimoto’s - Graves’ Can be used to guid fine-needle biopsy

Answer 9

US

Question 10

Emits gamma and beta radiation Beta radiation destroys tissues Used to assess thyroid and whole body scan Used to treat Graves’, toxic adenomas, and thyroid cancer

Answer 10

131iodine scan

Question 11

Enzymes that convert T4 into active T3 Occurs in the peripheral cells

Answer 11

5-Monodeiodinase DIO1 and DIO2

Question 12

In biochemical thyroid function tests, this is a tumor marker for MTC

Answer 12

calcitonin

Question 13

Decreased TSH Normal total or free T4

Answer 13

Subclinical hyperthyroidism

Question 14

Still significant health problem for about 1/3 of the world population 20 million people mentally handicapped d/t this Most preventable cause of mental impairment

Answer 14

Iodine Deficiency Disorders (IDD)

Question 15

Action is primarily mediated by nuclear receptors regulating gene transcription

Answer 15

Thyroid hormones

Question 16

Uptake of iodine tracer can be quantified to obtain estimate of ___ Radioiodine uptake

Answer 16

metabolic function

Question 17

Thyroid hormone receptors in the gut Non-steroid hormone receptor

Answer 17

TRbeta1

Question 18

Enzyme that converts T4 into rT3 (not biologically active)

Answer 18

5-Monodeiodinase DIO3

Question 19

Thyroid hormone receptors in the thyroid Non-steroid hormone receptor

Answer 19

TRbeta2

Question 20

Emits gamma radiation to be used in thyroid scanning

Answer 20

99technetium scan

Question 21

Damage tissue and are emitted in a 131iodine scan Used to treat hyperthyroidism

Answer 21

beta particles

Question 22

Stimulates growth and function of thyroid follicular cells resulting in the production of T4 and T3

Answer 22

TSH

Question 23

Most active thyroid hormone that does most of the work

Answer 23

T3

Question 24

Autoimmune thyroid destruction

Answer 24

Hashimoto’s thyroiditis

Question 25

Enzyme that forms iodine with thyroglobulin into T3/T4

Answer 25

TPO

Question 26

Emits gamma radiation Used to assess thyroid function and whole body scan

Answer 26

123iodine scan

Question 27

Decreased TSH Elevated total or free T4

Answer 27

Hyperthyroidism

Question 28

In biochemical thyroid function tests, displays antibodies to TSH receptors

Answer 28

Graves' Disease

Question 29

Thyroid hormone receptors in the heart Non-steroid hormone receptor

Answer 29

TRalpha1 and 2

Question 30

Hypoechoic signal, irregular borders, and microcalcifications on US point towards..

Answer 30

Thyroid cancer

Question 31

The more thyroid tissue, the higher the ___ Detectable amounts = residual or recurrent thyroid cancer tissue Increase may only be detectable under conditions of high TSH

Answer 31

TG level

Question 32

Transports thyroid hormones into peripheral cells from the bloodstream when they are free Can be mutated, esp. at the BBB leading to central hypothyroidism

Answer 32

Thyroid hormone transporter

Question 33

Binding proteins of T4/T3 \>99% of T4/T3 is protein bound

Answer 33

TBG (thyroid-binding globulin) \> TTR \> Albumin

Question 34

Negative regulation of the hypothalamic-pituitary-thyroid axis is controlled by..

Answer 34

T3 Somatostatin Dopamine

Question 35

~10% of normal individuals have these ~20% of pts w/ thyroid cancer have these Can interfere with the TG measurement Can be an indicator of residual or recurrent thyroid cancer tissue

Answer 35

Thyroglobulin Abs

Question 36

In biochemical thyroid function tests, this is a tumor marker for PTC, FTC

Answer 36

thyroglobulin

Question 37

Most common cause worldwide of thyroid disorders

Answer 37

Iodine deficiency