Thyroid Gland Functions and Disease

Question 1

Peripheral conversion of T4 to T3 is done by what enzyme?

Answer 1

Deiodinase

Question 2

Which deiodinase type is predominantly in the peripheral tissues?

Answer 2

Type 1

Question 3

During fasting, would you expect more or less conversion of T4 to T3.

Answer 3

Less

Question 4

What factors are associated with increase in conversion of T4 to T3

Answer 4

Obesity
cold exposure
hyperthyroid

Question 5

What factors are associated with decrease in conversion of T4 to T3?

Answer 5

Pregnancy
fasting
beta blockers
hepatic and renal failure
aging
hypothyroid

Question 6

How many Na comes in with I- in the NIS?

Answer 6

2 Na.

Question 7

What aa is the precursor for thyroglobulin?

Answer 7

Tyrosine

Question 8

What what channel does I- go from the cell to the colloid?

Answer 8

Pendrin

Question 9

Via what transport mechanism do TG-T3-T4 bound complex get inside the cell after TSH stimulation?

Answer 9

Pinocytosis inside a endosome.

Question 10

NIS can be blocked by what drug?

Answer 10

Percholarate, thiocynate.

Question 11

PTU is an effective treatment for hyperthyroidsim which works by blockig action of what enzyme?

Answer 11

peroxidase

Question 12

High levels of I- inhibits organification and synthesis of thyroid hormones. this effect is known as

Answer 12

Walff-Chaikoff

Question 13

Of the iodide that comes into the thyroid gland is stored in what form?

Answer 13

Stored iodinated as tyrosines of thyroglobulin inside the colloid of follicular lumen.

Question 14

With iodine deficiency, how long can you go without showing signs of hypothyroidism?

Answer 14

2-3 months

Question 15

Which thyroid hormone binding protein brings the thyroid hormone to the brain?

Answer 15

Transthyretin.

Question 16

Thyroxine-binding protein (TBG) has a higher affinity for which thyroid hormone (T3 or T4?

Answer 16

T4

Question 17

Describe the steps to T3 resin uptake test.

Answer 17

1. Obtain TBG w/bound T4 from serum.
2. Add unbound and labeled T3
3. Incubate - Allow binding to take place
4. Add Anti T3, or non specific resin which adsorbs T3.
5. From solution, remove TBG w/bound T4 and labeled T3
6. Precipitate the adsorbed T3

Question 18

During hyperthyroidsim, what would be levels of T4 and T3 resin uptake (increased or decreased)

Answer 18

Both increased

Question 19

During hypothyroidsim, what would be the levels of T4 and T3 resin uptake (increasd or decrease)

Answer 19

Both decreased

Question 20

During High TBG levels, would be the levels of T4 and T3 resin Uptake?

Answer 20

T4 is increased

T3 resin uptake is decreased

Question 21

During low TBG levels, what would be the level of T4, T3 resin uptake, increase or decrease.

Answer 21

decreased T4

increased T3 resin uptake

Question 22

During hepatic failure, what would be the levels of T3 resin uptake and TBG?

Answer 22

TBG is decreased. T3 resin uptake increased

Question 23

Druig pregnancy what would be the levels of TBG and T3 resin uptake

Answer 23

TBG is increased

T3 resin uptake is decreased.

Question 24

DUring pregnancy, a person is said to be clinically euthyroid, why?

Answer 24

During pregnancy TBG levels increase and so bound T3 and T4 increases, and free ones decrease. And since free ones decreased, the body sense that as deficiency and so they make more T3 and T4.. So overlll total T3 and T4 increase, but the levels of free physiologically active T3 and T4 remains realtively normal (euthyroid)

Question 25

What factors stimulate thyroid hormone secretion?

Answer 25

1. TSH 2. Pregnancy 3. Thyroid-stimulating immunoglobulins

Question 26

What factors inhibit thyroid hormone secretion?

Answer 26

1. Iodide deficiency 2. deiodinase deficiency 3. Excessive iodide intake (Wolff-Chaikoff effect) 4. percholorate, thiocyanate Prophylthiouracil 6. Decreased TBG levels (e.g. liver disease)

Question 27

Thyroid hormones stimulates production of new proteins in it's target tissues/cells. What are some example of the types of proteins thyroid hormone would stimulate the production of?

Answer 27

- Na/K ATPase -transport proteins -B-adrenergice receptors lysosomal enzymes -protlytic protiens -structural proteins

Question 28

Thyroid hormone stimulates the production of what in cardiac muscle cells?

Answer 28

- myosin - beta-adrenergic receptors - Ca ATpase

Question 29

In the liver and adipose tissue, thyroid hormones induce the synthesis of what types of enzymes?

Answer 29

Metabolic enzymes.

Question 30

Name one thing, thyroid hormone does in each of these systems: 1. Growth 2. CNS 3. BMR 4. metabolism 5. Cardiovascular

Answer 30

1. Increase growth formation and bone maturation 2. Maturation of CNS 3. Increase Na/K Atpase; O2 consumption; heat production and BMR 4. Increase glucose absorption, glycogenolysisi, gluconeogeneiss, lipolysis, protien synthesis and degradation (net catabolic) 5. Increase CO

Question 31

in response to thyroid hormone the increase in basal metabolic rate is mainly attributed to the increased activity of _

Answer 31

Na/K ATPase leading to increased O2 consumption and heat production

Question 32

In hypothyroidism, how would the blood cholesterol concentration change? Increase or decrease?

Answer 32

Increase.

Question 33

what hormone is required for the conversion of carotene to vitamin A

Answer 33

Thyroxine?

Question 34

What cardiac receptors do thyroid hormone stimulate/inhibit

Answer 34

THyroid hormone has both chronotorpic and ionotropic effect on cardiac receptors. It will stimulate beta adrenergic receptors while inhibiting muscarinic receptors.

Question 35

A new born baby presents with feeding problems, respiratory difficulty, tongue, curse facial features, growth retardation, mental retardation, jaundice, dry skin, hypotonia. what is the the likely diagnosis?

Answer 35

Cretinism

Question 36

What causes the exophthalmos, and periorbital edema as seen in Graves disease?

Answer 36

Due to recognition by the anti-TSH receptor antibodies of a similar epitope within the orbital cells.

Question 37

What three findings confirms graves disease?

Answer 37

1. elevated serum free and total T4 and T3 2. Clinical signs of goiter 3. Ophthalmopathy 4. Low TSH 5. serum levels of TSI

Question 38

Circulating levels of what proteins distinguishes Graves disease from adenoma of pituitary thyrotrophs?

Answer 38

TSI

Question 39

A patient had blood drawn to diagnose his thyroid issues. the following were seen: decreased TSH, Increased T3/T4, and positive for TSI, and radioactive iodine uptake test showed increased uptake. What is the diagnosis?

Answer 39

Graves Disease

Question 40

What disease is likely to be associated with the following finding? Increased TSH, decreased or normal T3/T4 and positive for antithyroid antibody.

Answer 40

Hashimoto

Question 41

What disease is likely to be associated with the following findings: decreased TSH, decreased T3/T4, and negative for antithyroid antibody

Answer 41

Pituitary abnormality