Thyroid and Diabetes intro

Question 1

What is the chemical name for the hormone T3?

Answer 1

Liothyronine

Question 2

Which is more pharmacologically active, T4 or T3? Which is more abundant?

Answer 2

T3 is more active, T4 is more abundant

Question 3

Outline the synthesis of thyroid hormone from peroxidase

Answer 3

Peroxidase – oxidation of dietary iodine – iodination of tyrosine – thyroid hormone

Question 4

What is thyroid hormone stored as?

Answer 4

Thyroglobulin

Question 5

What releases TRH and TSH?

Answer 5

TRH – hypothalamus

TSH – pituitary

Question 6

What is thyroid binding globulin?

Answer 6

The plasma protein that binds the majority of circulating T3 and T4

Question 7

Name two common increasers of TBG

Answer 7

Pregnancy and oral contraceptives

Question 8

Name a common decreaser of TBG

Answer 8

Anabolic steroids

Question 9

List three functions of thyroid hormone

Answer 9

Stimulates protein synthesis, increases metabolic rate, increases sensitivity to catecholamines

Question 10

How long does it take T4 (levothyroxine) to reach max efficacy?

Answer 10

10 days

Question 11

How long does it take T3 (Liothyronine) to reach max efficacy?

Answer 11

24 hours

Question 12

Which is “slower on and slower off”, T3 or T4?

Answer 12

T4

Question 13

How does the thyroid hormone dose change in pregnant individuals?

Answer 13

Pregnant females require nearly 50% more thyroid hormone due to increased TBG production

Question 14

What is a typical initial dose of Synthroid?

Answer 14

50 to 100 µg adjusted every 30 days until TSH is normal

Question 15

Why should thyroid hormone be taken on an empty stomach?

Answer 15

It sticks to food and is excreted

Question 16

In which case should T3 be administered?

Answer 16

In thyroid emergencies (myxedema coma), T3 can be given IV

Question 17

What is the effect of administering too much thyroid hormone?

Answer 17

Pseudo-hyperthyroidism causing a fib

Question 18

How is pseudohyperthyroidism treated?

Answer 18

Discontinue medicine for seven days then recommence at lower dose

Question 19

Why is Synthroid the preferred treatment for hypothyroidism?

Answer 19

Generic thyroid hormone may be significantly less biologically active

Question 20

What is the chemical name for T4 hormone?

Answer 20

L – thyroxine

Question 21

What are the hyperthyroid medications (Methimazole and PTU) method of action? How do they differ?

Answer 21

Inhibits the oxidation (activation) of thyroid hormone
Methimazole does not affect peripheral conversion of T4 to T3, while PTU cannot take effect until preformed T4 -T3 is exhausted

Question 22

Which of the two hyperthyroid medications is taken 1 x a day and which is taken 3 x a day?

Answer 22

Methimazole – 1x a day

Propylthiouracil- 3x a day

Question 23

Which hyperthyroid medication can be used to treat thyroid storm in high doses?

Answer 23

PTU – inhibits peripheral conversion of T4 to T3

Question 24

What are the most common adverse effects of PTU?

Answer 24

Rash, dysphasia, agranulocytosis

Question 25

When is iodine used?

Answer 25

Before thyroid surgery to firm up thyroid (negative feedback loop within thyroid causes involution)

Question 26

What is the typical dose of iodine given preop?

Answer 26

Potassium iodide 60 mg Q8 hours for 10 to 14 days

Question 27

When and how is radioactive iodine used?

Answer 27

Can be used to treat graves disease: selectively up taken by thyroid tissue, slowly destroys tissue, often induces hypothyroidism

Question 28

How is thyroid storm most effectively treated?

Answer 28

With a nonselective beta blocker (Propanolol) IV or PO

Question 29

How is thyroid storm treated (other than beta blocker)?

Answer 29

High-dose dexamethasone steroid will inhibit T4 conversion to T3

Question 30

What is a risk of using dexamethasone to treat thyroid storm?

Answer 30

Can cause hyperglycemia due to steroid effect on blood glucose

Question 31

What is hyperinsulinemia?

Answer 31

Increased production of insulin in people who consume excessive amounts of sugar (leads to hyperglycemia from down regulation)

Question 32

Which cells secrete in store insulin?

Answer 32

Beta islet cells of pancreas

Question 33

How is synthetic insulin made?

Answer 33

Either enzymatic modification of porcine insulin or recombinant technology

Question 34

What bacteria is used in recombinant technology to produce insulin?

Answer 34

E. coli

Question 35

Describe the 3 biological effects of insulin

Answer 35

Activates glucokinase and glucose phosphatase Causes conversion of glucose to glycogen Enhances arachidonic acid and K+ entry into cells

Question 36

What is the general dosage rule for insulin?

Answer 36

One unit of insulin per kilogram of body weight per day