Thyroid disease

Question 1

Where is the thyroid gland situated?

Answer 1

In front of the trachea, just below Adam’s apple

Question 2

What are the functional units of the thyroid gland called?

Answer 2

Thyroid follicles

Question 3

What are thyroid follicles filled with?

Answer 3

Thyroglobulin - acts as a store for iodide

Question 4

What is iodide needed for?

Answer 4

Production of thyroid hormone

Question 5

Parafollicular C cells are also found in the thyroid gland. Where are they situated?

Answer 5

Between follicles

Question 6

What is the role of parafollicular C cells?

Answer 6

Secrete calcitonin - involved in calcium homeostasis

Question 7

Which enzyme converts T4 into T3?

Answer 7

Iodothyronine deiodinases

Question 8

Where is DIO1 predominantly found?

Answer 8

Liver, kidney, muscles and thyroid gland

Question 9

Where is DIO2 predominantly found?

Answer 9

CNS and pituitary thyrotropes

Question 10

Which DIO produces most of the circulating T3?

Answer 10

DIO1

Question 11

Which DIO controls intracellular T3 concentration?

Answer 11

DIO2

Question 12

Which DIO produces rT3?

Answer 12

DIO3

Question 13

How many genes do thyroid hormone receptors have?

Answer 13

2 - THRA and THRB found in the nucleus

Question 14

Which receptor do thyroid hormone receptors form a heterdimer with?

Answer 14

Retinoid X receptor

Question 15

What are the 5 biological elements of thyroid hormone?

Answer 15

Control of metabolic rate
Growth
Foetal development
CV effects
Musculoskeletal effect

Question 16

What are the symptoms of hypothyroidism?

Answer 16

Lethargy
Hair loss
Memory loss
Weight gain

Question 17

What are the 3 thyroid function tests that can be performed to diagnose hypothyroidism?

Answer 17

Unbound T4
TSH
Thyroid peroxidase antibody

Question 18

In primary hypothyroidism, what happens to unbound T4 and TSH?

Answer 18

Increased TSH

Decreased unbound T4

Question 19

What are carbimazole and propylthiouracil used to treat and how do they work?

Answer 19

Hyperthyroidism

Work by interfering with thyroid hormones synthesis by inhibiting thyroid peroxidase activity

Question 20

What is used to treat hypothyroidism?

Answer 20

Levothyroxine

Question 21

Why may B-blockers need to be given TDS/QDS in hyperthyroidism?

Answer 21

Because metabolism is increased

Question 22

What is B-blockers place in therapy in hyperthyroidism?

Answer 22

Adjuvant therapy - rapid relief of symptoms (tachycardia, tremor etc.)

Question 23

Which 3 drugs can cause thyroid disease?

Answer 23

Iodine
Amiodarone
Lithium

Question 24

Which thyroid disease can iodine deficiency cause?

Answer 24

Hypothyroidism

Question 25

How can amiodarone cause mild hyperthyroidism?

Answer 25

Blocks conversion of T4 to T3 therefore increases TSH and T4

Question 26

How can amiodarone cause hypothyroidism?

Answer 26

Inhibition of the synthesis and release of T3 and T4

Question 27

How does lithium cause hypothyroidism?

Answer 27

Inhibits iodine uptake and prevents T3 and T4 release

Question 28

Which two hormones regulate calcium homeostasis?

Answer 28

Calcitronin | Parathyroid hormone

Question 29

What is the main function of calcitonin?

Answer 29

Reduce blood calcium concentration

Question 30

How many parathyroid glands do most people have?

Answer 30

four - located on posterior surface of thyroid gland

Question 31

What are the two cell types that parathyroid glands have?

Answer 31

Chief cells | Oxyphill cells

Question 32

What is the function of parathyroid hormone?

Answer 32

Increases blood calcium concentration

Question 33

How does PTH increase blood calcium conc?

Answer 33

Indirectly stimulating osteoclasts to release more Ca2+ from bone Increasing renal calcium reabsorption Increasing vitamin D production -> stimulates Ca2+ uptake from intestine

Question 34

How does calcitonin reduce blood calcium concentration?

Answer 34

Reduces osteoclast activity to reduce bone resorption and allow rapid bone deposition by osteoblasts

Question 35

Name some disease of calcium homeostasis

Answer 35

``` Osteoporosis Rickets Primary hyperparathyroidism Secondary hyperparathyroidism Paget's disease ```