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Nutrition 2 (Semester I) > 6a. Endocrine Health - Thyroid > Flashcards

6a. Endocrine Health - Thyroid Flashcards

(106 cards)

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1
Q

What is TRH?

A

Thyrotropin releasing hormone

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2
Q

What does TRH do?

A

Stimulates TSH release from the anterior pituitary gland

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3
Q

What does TSH do?

A

Stimulates thyroid hormone production from the thyroid gland - T4 and T3
Activates iodide uptake via the Na/iodide symporter (SIS)

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4
Q

What percentage of thyroid hormone is T4?

A

90%

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5
Q

What is the alternative name for T4?

A

Thyroxine

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6
Q

Which of T4 and T3 is the strongest, more active hormone?

A

T3 - 4x the strength of T4

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7
Q

What does T3 do?

A

Increases growth
Bone development
CNS development
Increases BMR/HR
Activates metabolism

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8
Q

What does RT3 do?

A

Protects tissues from excess thyroid hormones
Biologically inactive - puts the handbrake on T3

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9
Q

What are iodothyronine deiodinases?

A

Selenoproteins that regulate thyroid hormone homeostasis

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10
Q

What does deiodinase 1 and 2 do (D1/D2)?

A

Convert T4 to T3

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11
Q

What does deiodinase 3 do (D3)?

A

Converts T4 to RT3

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12
Q

What does thyroid peroxidase (TPO) do?

A

Enzyme that helps produce T4 and T3
(catalyses iodination of tyrosine residues in thyroglobulin)

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13
Q

Which nutrients are needed to make TPO?

A

Tyrosine
Iodine
Iron

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14
Q

Which minerals are needed as co-factors in the synthesis of enzymes and thyroid hormones?

A

Se
Zn
Cu

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15
Q

Which vitamins are needed to support thyroid hormone synthesis and function?

A

ACE
B2, B3, B6, B12

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16
Q

What is the role of vit D in thyroid synthesis?

A

Immune modulation in AI thyroid disorders and VDR polymorphism

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17
Q

Examples of iodine rich foods

A

Sea veg
Ocean fish
Shellfish
Eggs
Dairy

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18
Q

What is the cause of iodine deficiency?

A

Dietary deficiency

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19
Q

Who is more at risk of iodine deficiency?

A

Low/no fish or dairy in diet
Pregnant women
Vegans

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20
Q

Why can high goitrogen foods cause thyroid disorders?

A

Goitrins, thiocyanates and nitriles in the foods reduce iodine uptake and have anti-TPO activity

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21
Q

Examples of goitrogen foods

A

Raw brassicas
Soya (fermented ok)
Millet
Peanuts
Pine nuts

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22
Q

How can people consume excess iodine?

A

Over-iodised salt
Animal milk rich in fortified iodine
Iodine-containing supplements
Radiocontrast dyes
Some medications

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23
Q

What is the Wolff-Chaikoff effect?

A

Helps reject excess iodine

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24
Q

What can inhibited Wolff-Chaikoff effect lead to?

A

Subclinical or clinical hypothyroidism

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25
Where is T4 converted to T3 or RT3?
Liver Kidneys
26
How are the thyroid hormones metabolised?
Deiodination Sulphation Glucuronidation
27
Which thyroid hormone decreases if RT3 increases?
T3
28
In which situations does an increase in T4 to RT3 occur?
Chronic illness - to low metabolism High stress Zn/Se/Fe deficiency Fasting/significant calorie restriction Advancing age
29
Which thyroid pathology does increased RT3 present as?
Hypothyroidism
30
What do HPT disrupters interfere with?
HPT axis Thyroid hormone synthesis, secretion, transportation, metabolism and function
31
Examples of HPT disrupters
Fluoride Chlorine Pesticides BPAs Phthalates Bromine Glyphosate
32
Ways to avoid HPT disrupters
Drink filtered water Fluoride free toothpaste Eat organic Avoid farmed fish/processed foods Limit time in chlorinated pools Avoid plastic packaging
33
Examples of medications that exert effects on thyroid function
Dopamine/glucocorticoids - decrease TSH secretion Beta blockers - reduce T4 to T3 Diuretics/NSAIDs - reduce T4 to T3 binding Oestrogen - increase thyroglobulin
34
Why does gut dysbiosis negatively effect thyroid function?
Microbes regulate iodine uptake and degradation
35
What intestinal imbalances are common in AITD?
Low SCFA production Elevated zonulin (intestinal permeability) Elevated serum LPS (chronic low grade inflammation)
36
Optimal range of TSH in testing
0.4 - 2.5
37
Optimal range of total T4 in testing
70 - 150
38
Optimal range of free T4 in testing
12.8 - 19.5 pg/ml
39
Optimal range of free T3 in testing
3.2 - 4.5
40
Optimal range of RT3 in testing
11 - 18 ng/dl
41
How is subclinical hypothyroidism interpreted in testing?
High TSH Normal T4 Normal T3
42
How is hypothyroidism interpreted in testing?
High TSH Low T4 Low T3
43
How is subclinical hyperthyroidism interpreted in testing?
Low TSH Normal T4 Normal T3
44
How is hyperthyroidism interpreted in testing?
Low TSH High T4 High T3
45
How is secondary hypothyroidism interpreted in testing?
Low TSH Low T4 Low T3
46
What is the best test for testing iodine status?
Urine iodine test
47
What should iodine levels be in children/adults?
100-199 mcg/L
48
What should iodine levels be in pregnancy?
150-249 mcg/L
49
What iodine level is considered as insufficiency?
<100 mcg/L
50
What iodine level is considered as severe deficiency?
<20 mcg/L
51
What signs of hypothyroidism can be seen during a physical exam?
Goitre Dry skin Nail beading Thinning eyebrows Hair loss Low BP Bradycardia (<60 BPM)
52
Which SNPs on a thyroid report may suggest a thyroid imbalance?
HLA - AI TNF - inflammation SLCO1B - transport of hormones into cells VDR - vit D as a co-factor BCO1 - retinol as a co-factor SULT/UGT - detoxification
53
What is primary hypothyroidism?
Pathology is occurring within the thyroid gland TSH is high due to low T4/T3
54
What is secondary hypothyroidism?
Pathology is occurring within the pituitary gland Low TSH to signal to thyroid gland to release T4/T3
55
What is tertiary hypothyroidism?
Inadequate TRH
56
What is peripheral hypothyroidism?
Insensitivity to thyroid hormones
57
What is subclinical hypothyroidism?
Slightly high TSH and normal T4/T3
58
General signs/symptoms of hypothyroidism
Fatigue Weight gain Puffy face Intolerance to cold Joint/muscle pain/weakness Dry skin Hair loss/thinning Constipation Fertility problems Goitre Bradycardia
59
Risk factors/causes of hypothyroidism
Iodine deficiency/excess Women Age Lack of nutrients - Fe, Se, Tyrosine, Zn, D, C, Cu, B2/3/6/12 Chronic stress - inhibits TSH release Infection/inflammation Alcohol Smoking Drug induced - amiodarone/lithium
60
What is Hashimoto's thyroiditis?
AI disease Attacks thyroid tissue causing reduced thyroid hormones
61
What is the ratio of women:men of getting Hashimoto's?
10:1
62
What are the testing markers for Hashimoto's?
High TSH Low T4 Increased anti-thyroid peroxidase (TPO) antibodies
63
Which two infections are implicated in Hashimoto's?
EBV H. pylori (as triggers for the AI)
64
What are the risk factors/causes of Hashimoto's?
Excess iodine Coeliac disease Genetic polymorphisms - VDR, MTHFR Heavy metals Triclosan - found in personal care products
65
What is the allopathic treatment for Hashimoto's?
Levothyroxine (synthetic T4)
66
When is it best to take levothyroxine?
Empty stomach in the morning Take food/other drinks at least 1hr after
67
What can affect the absorption of levothyroxine?
Coeliac disease Coffee PPIs
68
Common triggers and mediators in the development of thyroid disorders
Iodine status Micronutrient insufficiencies Intestinal permeability Inflammation Food sensitivities Goitrogens HPA axis imbalance (stress) SNPs Medications Environmental toxins Radiation Surgery
69
Naturopathic approach to hypothyroidism
Address micronutrient status Review iodine status Optimise digestion Support methylation Remove thyroid disruptors Address possible dysbiosis Increase SCFA producers Address stress Support detoxification/elimination Avoid heavy metals Assess for coeliac disease Identify food intolerances Increase exercise Reduce inflammation Blood sugar balance Reduce goitrogenic compounds Address intestinal permeability
70
Why is Zn needed for thyroid support?
Co-factor for D2 TRH synthesis
71
How could Zn deficiency be indicated on a test?
Low T3 High RT3
72
Supplement dosage for Zn in thyroid support
15-30 mg/day
73
Why is Fe needed for thyroid support?
TPO is a haem-containing enzyme needed in initial steps of hormone synthesis Deficiency decreases T4 and T3
74
Supplement dosage for Fe in thyroid support
10mg - maintenance 30mg - deficient (test before)
75
Why is iodine needed for thyroid support?
Modulates thyroid response to TSH
76
Supplement dosage for iodine in thyroid support
150-400mg/day
77
Why is Se needed for thyroid support?
AO Anti-inflammatory Increases T3
78
Supplement dosage for Se in thyroid support
150-200mg/day
79
Why is tyrosine needed for thyroid support?
Thyroglobulin precursor
80
Supplement dosage for tyrosine in thyroid support
200-500mg/day
81
Why is vit A needed for thyroid support?
Modulates thyroid hormone receptor function
82
What can insufficiency in vit A cause?
Increases TSH Reduces iodine uptake in thyroid
83
What can cause vit A insufficiency?
Low intake BCO1 SNP
84
Supplement dosage for vit A for thyroid support
2000 iu/day
85
What role does vit D have in thyroid support?
Immune-modulatory
86
Supplement dosage for vit D for thyroid support
2000 iu/day
87
Herbal approaches to hypothyrodism
Nigella sativa (1g/day) - reduces TSH/TPO Thyroid glandulars - provides T4/3, relevant AAs and micronutrients Ashwagandha - improves TSH/T4/T3 levels Guggul - enhances iodine uptake
88
What is hyperthyroidism?
Increased levels of thyroid hormones
89
What are the two sub-divisions of hyperthyroidism?
Thyrotoxicosis Thyroiditis
90
What is thyrotoxicosis?
Increased synthesis of thyroid hormones
91
What is the key cause of thyrotoxicosis?
Grave's disease (80%)
92
What is thyroiditis?
Increased release of stored thyroid hormones due to thyroid damage
93
What are the key causes of thyroiditis?
Viral infections AI
94
Who is more affected by hyperthyroidism?
Women (10:1)
95
Key signs/symptoms of hyperthyroidism
Weight loss Thirst Diarrhoea Tachycardia Palpitations SOB Goitre Irritability Nervousness Anxiety Insomnia Warm, moist skin Sweating Heat intolerance
96
What is Grave's disease?
AI hyperthyroidism
97
What two antibodies are present in Grave's disease?
TRAbs TPO
98
Characteristic signs/symptoms of Grave's disease
Red, swollen eyes Eyelid retraction Eyeball protrusion Excess eye watering Double vision Painless rash - lower legs/top of feet
99
Causes/risk factors for hyperthyroidism
Family history Stress Inflammation Excess iodine intake Dysbiosis Food allergy/intolerance Heavy metals Smoking Infections Vit D/Se/CoQ10 deficiency
100
What FT3/FT4 ratio distinguishes Grave's from thyroiditis?
>0.3
101
What markers will be present in thyroiditis?
Raised CRP and ESR
102
Natural approach to support hyperthyroidism
AO - ACE, Se, Zn, D Energy - B vits, carnitine, Mg, CoQ10 Glutathione support Avoid iodine Increase goitrogens Reduce inflammation (increase O3 but not via fish) Quercetin Support blood sugar balance Support stress/HPA axis Address gut health Support sulphation Support glucuronidation Increase calorie intake - nuts/seeds/avocado/olives/protein rich
103
Why is carnitine important in hyperthyroidism?
Antagonises thyroid hormones inhibiting T4/T3 Prevents/reverses muscle weakness
104
Supplement dosage of carnitine to support hyperthyroidism
2000-4000mg/day
105
Why is vit D important in hyperthyroidism?
Immune modulator May slow disease progression
106
Herbal approaches to hyperthyroidism
Passionflower/valerian - nervines - reduce stress Ashwagandha Mg/theanine - reduce anxiety Lemon balm - blocks thyroid hormone activity

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