General Endocrine Health

Question 1

Describe the HPT axis

Answer 1

Hypothalamus-Pituitary-Thyroid
TRH (Thyrotropin-Releasing Hormone) stimulates TSH (Thyroid-stimulating hormone). TSH stimulates thyroid hormone release of T4 and T3

Question 2

What are Iodothyronine Deiodinases?

Answer 2

Selenoproteins that remove iodine, contain selenium and that regulate hormone homeostatis

Question 3

Name the proteins that are dependant on selenium and needed for T4-T3 conversion

Answer 3

D1, D2 = T3

D3=RT3

Question 4

Which Thyroid homrone is the ‘inactive’ or ‘weak’ form with aprrox. 90% secreted?

Answer 4

T4 (Thyroxine)

Question 5

What nutrients are needed for thyroid hormone synthesis?

Answer 5

Tyrosine
Iodine
Fe
Selenium
Vitamin D
Zn
Vitamins A, C, E, B2, B3, B6, B12
Cu

Question 6

What can cause an iodine deficency?

Answer 6

Dietary deficines
High goitrogen intake - soya, millet, peanuts, pine nuts, raw brassicas
Low/no dairy/Fish, pregnancy, vegans

Question 7

What can cause iodine excess?

Answer 7

Consumption of over-idoised salt, animal milk,
iodine-containing supplements
Radiocontrast dyes
Medications

Question 8

Name some HPT disruptors

Answer 8

Pesticides
Glyphosphate
PCBs
Bisphenols (BPA)
Phthalates
Perchlorates
Halogens
- fluoride
- chlorine
- bromine

Question 9

List ways in which thyroid disruptors can be avoided

Answer 9

Filtered water
fluoriode-free toothpaste
organic
avoid farmed fish
avoid procesed foods and beverages
limit time in chlorinated pools
avoid plastic packaging
organic textiles
natural cleaning products

Question 10

List the classifications of Hypothyroidism

Answer 10

Primary
Secondary
Tertiary
Peripheral
Subclinical

Question 11

What are the 2 levels of Hyperthyroidism?

Answer 11

Thyrotoxicosis

Thyroiditis

Question 12

Describe the GLUT (glucose transporter) proteins:
GLUT1
GLut4
Glut2

Answer 12

Glut 1- basal glucose uptake without insulin
Glut 4 - insulin regulated - increases glucose up-take 20-30
Glut 2 - mediated glycolosis and gluconeogensis

Question 13

List the different types of Diabetes Mellitus

Answer 13

T1DM
T2DM
Prediabetes
Gestational diabetes
Secondary diabetes

Question 14

What range on a HbA1c test determines diabetes?

Answer 14

48mmol/mol or over

6.5%

Question 15

What range on a HbA1c test indicates prediabetes?

Answer 15

42-47mmol/mol

6.0-6.4%

Question 16

What is indicated as normal on a HbA1c test?

Answer 16

Anything less than 42

6.0%

Question 17

What kind of proteins are iodothyronine deiodinases?

Answer 17

Selenoproteins

Question 18

What enzymes are involved in the removal of iodine?

Answer 18

Iodothyronine deiodonases

Question 19

Which deiodinases convert T4 to T3?

Answer 19

D1 and D2

Question 20

What is TRH and what does it do?

Answer 20

Thyrotropin-releasing hormone, released from the hypothalamus stimulating the release of TSH

Question 21

What is TSH and what does it do?

Answer 21

Thyroid-stimulating hormone. Stimulates the release of T4 and T3. activates iodide uptake via the Sodium/Iodide symporter (SIS)

Question 22

What is SIS? What does it do?

Answer 22

Sodium/Iodide Symporter. A transmembrane glycoprotein needed for active transport of iodine into thyroid follicular cells

Question 23

What is T3? What does it do?

Answer 23

Triiodothyronine. 4 x the strength of T4.

• Increases growth, bone and CNS development
• Increases basal metabolic rate (BMR)
• Activates metaolism
• Increases heart rate

Question 24

What is T4? What does it do?

Answer 24

Thyroxine or Tetraiodothyonine. 90% secreted, weak and inactive form.

Question 25

What is RT3? What does it do?

Answer 25

Reverse T3. Biologically inactive. Protects tissues from excess thyroid hormones.

Question 26

What nutrient do D1, D2 and D3 depend on?

Answer 26

Selenium

Question 27

Over time hyperthyroid medication can induce hypothyroidism. What do the following medications do to the thyroid? - Dopamine - Lithium - Glucocorticoids

Answer 27

Reduce TSH

Question 28

Over time hyperthyroid medication can induce hypothyroidism. What do the following medications do to the thyroid? - Phenytoin - Rifampicin

Answer 28

Affect T4 and T3

Question 29

Over time hyperthyroid medication can induce hypothyroidism. What do the following medications do to the thyroid? - Beta-blockers - Amiodarone

Answer 29

Reduce T4 and T3

Question 30

Over time hyperthyroid medication can induce hypothyroidism. What do the following medications do to the thyroid? - NSAIDs - Diuretics

Answer 30

Reduce T4 and T3 binding

Question 31

Over time hyperthyroid medication can induce hypothyroidism. What do the following medications do to the thyroid? - Oestrogen - Tamoxifen

Answer 31

Increase thyroglobulin

Question 32

List some iodine-rich foods

Answer 32

``` Seaweed and algae (sea vegetables) Ocean fish Shellfish Cod Scallops Eggs Dairy ```

Question 33

List some Goitrogens

Answer 33

``` Soya Millet Peanuts Pine nuts Raw Brassicas ```

Question 34

Do goitrogens increase or decrease iodine?

Answer 34

decrease

Question 35

What is TPO? And what does it do?

Answer 35

Thyroid Peroxidase. Catalyase iodination of Tyrosine to form T4 and T3

Question 36

Why is Fe important for thyroid health?

Answer 36

Thyroid Peroxidase is haem-dependant. TPO is needed to convert tyrosine to T4 and T3.

Question 37

Name 2 enzyme co-factors needed for thyroid receptor function

Answer 37

Selenium and Zinc

Question 38

Which nutrient is a cofactor in deiodinase enzymes?

Answer 38

Copper

Question 39

How will high goitrogen intake cause iodine deficiency?

Answer 39

Blocks iodine uptake

Question 40

What is the Wolff-Chairkoff Effect?

Answer 40

A cause of excess iodine in the body. A large amount of dietary iodine inhibits thyroid hormone synthesis

Question 41

What is the base material for thyroid hormones produced in the thyroid gland?

Answer 41

thyroglobulin

Question 42

Where is T3 made?

Answer 42

Peripheral tissue

Question 43

What is Peripheral Conversion?

Answer 43

When T4 is converted to T3 or RT3 in the liver and kidneys (peripheral tissues)

Question 44

How are thryoid hormones metabolised?

Answer 44

deoidination, glucoronidation, sulphation

Question 45

__ is highly bound (99.98%), 0.02% circulates freely. | __ is slightly less protein bound (99.8%), 0.2% as free fraction.

Answer 45

T4 is highly bound and circulates freely | T3 is slightly less protein bound

Question 46

How much of T4 and T3 does the thyroid secrete on a daily basis?

Answer 46

T4-80-100mcg | T3-10mcg

Question 47

What is RT3?

Answer 47

Biologically inactive thryoid hormone that binds to T3 receptors, reducing T3

Question 48

Increase RT3 can present as

Answer 48

Hypothyroidism

Question 49

Increase T4 converting to RT3 increases in what circumatances?

Answer 49

Chronic illness | High stress