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Endocrine Health > General Endocrine Health > Flashcards

General Endocrine Health Flashcards

1
Q

Describe the HPT axis

A

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

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2
Q

What are Iodothyronine Deiodinases?

A

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

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3
Q

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

A

D1, D2 = T3

D3=RT3

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4
Q

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

A

T4 (Thyroxine)

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5
Q

What nutrients are needed for thyroid hormone synthesis?

A 
Tyrosine
Iodine
Fe
Selenium
Vitamin D
Zn
Vitamins A, C, E, B2, B3, B6, B12
Cu
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6
Q

What can cause an iodine deficency?

A

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

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7
Q

What can cause iodine excess?

A

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

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8
Q

Name some HPT disruptors

A 
Pesticides
Glyphosphate
PCBs
Bisphenols (BPA)
Phthalates
Perchlorates
Halogens
- fluoride
- chlorine
- bromine
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9
Q

List ways in which thyroid disruptors can be avoided

A 
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
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10
Q

List the classifications of Hypothyroidism

A 
Primary
Secondary
Tertiary
Peripheral
Subclinical
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11
Q

What are the 2 levels of Hyperthyroidism?

A

Thyrotoxicosis

Thyroiditis

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12
Q

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

A

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

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13
Q

List the different types of Diabetes Mellitus

A 
T1DM
T2DM
Prediabetes
Gestational diabetes
Secondary diabetes
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14
Q

What range on a HbA1c test determines diabetes?

A

48mmol/mol or over

6.5%

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15
Q

What range on a HbA1c test indicates prediabetes?

A

42-47mmol/mol

6.0-6.4%

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16
Q

What is indicated as normal on a HbA1c test?

A

Anything less than 42

6.0%

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17
Q

What kind of proteins are iodothyronine deiodinases?

A

Selenoproteins

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18
Q

What enzymes are involved in the removal of iodine?

A

Iodothyronine deiodonases

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19
Q

Which deiodinases convert T4 to T3?

A

D1 and D2

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20
Q

What is TRH and what does it do?

A

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

21
Q

What is TSH and what does it do?

A

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

22
Q

What is SIS? What does it do?

A

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

23
Q

What is T3? What does it do?

A

Triiodothyronine. 4 x the strength of T4.

  • Increases growth, bone and CNS development
  • Increases basal metabolic rate (BMR)
  • Activates metaolism
  • Increases heart rate
24
Q

What is T4? What does it do?

A

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

25
Q

What is RT3? What does it do?

A

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

26
Q

What nutrient do D1, D2 and D3 depend on?

A

Selenium

27
Q

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

  • Dopamine
  • Lithium
  • Glucocorticoids
A

Reduce TSH

28
Q

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

  • Phenytoin
  • Rifampicin
A

Affect T4 and T3

29
Q

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

  • Beta-blockers
  • Amiodarone
A

Reduce T4 and T3

30
Q

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

  • NSAIDs
  • Diuretics
A

Reduce T4 and T3 binding

31
Q

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

  • Oestrogen
  • Tamoxifen
A

Increase thyroglobulin

32
Q

List some iodine-rich foods

A 
Seaweed and algae (sea vegetables)
Ocean fish
Shellfish
Cod
Scallops
Eggs
Dairy
33
Q

List some Goitrogens

A 
Soya
Millet
Peanuts
Pine nuts
Raw Brassicas
34
Q

Do goitrogens increase or decrease iodine?

A

decrease

35
Q

What is TPO? And what does it do?

A

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

36
Q

Why is Fe important for thyroid health?

A

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

37
Q

Name 2 enzyme co-factors needed for thyroid receptor function

A

Selenium and Zinc

38
Q

Which nutrient is a cofactor in deiodinase enzymes?

A

Copper

39
Q

How will high goitrogen intake cause iodine deficiency?

A

Blocks iodine uptake

40
Q

What is the Wolff-Chairkoff Effect?

A

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

41
Q

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

A

thyroglobulin

42
Q

Where is T3 made?

A

Peripheral tissue

43
Q

What is Peripheral Conversion?

A

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

44
Q

How are thryoid hormones metabolised?

A

deoidination, glucoronidation, sulphation

45
Q

__ is highly bound (99.98%), 0.02% circulates freely.

__ is slightly less protein bound (99.8%), 0.2% as free fraction.

A

T4 is highly bound and circulates freely

T3 is slightly less protein bound

46
Q

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

A

T4-80-100mcg

T3-10mcg

47
Q

What is RT3?

A

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

48
Q

Increase RT3 can present as

A

Hypothyroidism

49
Q

Increase T4 converting to RT3 increases in what circumatances?

A

Chronic illness

High stress

Endocrine Health (7 decks)

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