Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

MB2: Endocrinology > Thyroid physiology and pathology > Flashcards

Thyroid physiology and pathology Flashcards

(121 cards)

Start Studying
1
Q

describe embryology of the thyroid gland

A

midline thickening on tongue at week 4 migrating downwards

migrates in front of larynx with close proximity to PTH glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how many people have a pyramidal lobe

A

15%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what do C cells produce

A

calcitonin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

the point of the tongue at which the thyroid originally existed is a point called

A

foramen caecum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what hormones does the thyroid secrete

A

thyroxine
tri-iodothyronine
calcitonin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

autonomic innervation to the thyroid

A

PS - vagus nerve

S - from superior, middle, inferior sympathetic trunk ganglia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what arteries supply the thyroid

A

superior and inferior thyroid arteries

thyroidea ima

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what veins drain the thyroid

A

superior/middle thyroid veins to IJV

inferior thyroid vein to drain to BCV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what ligaments/muscles support the thyroid

A

berry ligament

strap muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is a basic follicle of thr thyroid

A

follicular cells surrounding central colloid mass

parafollicular cells around the outside

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe the thyroid pituitary hypothalamic axis

A

hypothalamus secretes TRH to ant pituitary that releases TSH and acts on thyroid tissue to secrete T3/4
excess T3/4 in peripheral tissues causes -ve feedback to act on TRH/TSH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

describe synthesis and release of T3/4 in the thyroid follicle

A

synthesis of thyroglobulin in follicular cell and storage in colloid
uptake and concn of iodide ions that are oxidised and pass to colloid mass
thyroglobulin is iodised to tyrosine with 1/2 iodines and binds to another with 2
colloid enveloped by microvilli on follicular cell and fuse with lysosomes to cleave T3/4 and release to bloodstream

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what thyroid hormone is secreted most and what one is most biologically active

A

T4 is secreted most but T3 is biologically active, so T4 is converted to T3 by liver/kidneys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

true/false - most thyroid hormones are found ‘free’ in blood

A

false - most are bound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what transport molecules are thyroid hormones bound to

A

thyroid binding globulin mainly

also thyroid binding pre albumin, albumin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what causes increase in TBG and how does this affect T4 concns

A 
pregnancy 
ora contraceptive 
tamoxifen 
Hep A 
chronic active hep
biliary cirrhosis 
increases total T4 but not FT4
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what causes decrease in TBG and how does this affect T4 concns

A 
androgens 
large dose glucocorticoids or cushings syndrome 
severe systemic illness 
chronic liver disease 
nephrotic syndrome 
decreases total T4 but not FT4
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

effects of thyroid hormones on metabolism?

A

increased BMR with increased number and size mitochondria, increased O2 and increased synthesis resp chain enzymes
increased lipolysis increased glycogenolysis and gluconeogenesis and decreased glycogenolysis - raised BG and insulin dependent glucose uptake
increased thermogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how does thyroid hormone aid in neural development

A

myelinogenesis and axon growth need thyroid hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what can imbalances in thyroid hormone do to behaviour

A

hypothyroidism can slow intellectual function and hyperthyroidism can cause nervousness, hyperkinesis and emotional lability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what effect does thyroid hormone have on the lungs, heart and sympathetic nervous system

A

increased response to NA/adrenaline by increased receptors

increased breathing rate and increased rate and force of heart contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

where are D1 de-ionase enzymes found and what does it do

A

breaks T4 to T3

found in liver and kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

where are D2 de-ionase enzymes found

A

heart, skeletal muscle, CNS, fat, thyroid, pituitary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

where are D3 de-ionase enzymes found and what does it do

A

break down T3 to inactive T2 and breaks T4 to inactive reverse T3 which is excreted rapidly
found in placenta, foetal tissue and brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what is the rough weight of the thyroid
15-25g
26
what vertebral level does the thyroid sit around
C5/6 and can extend to T1
27
failure of the thyroid to descend results in?
lingual thyroid
28
excess descent of the thyroid results in?
retrosternal thyroid
29
histology of follicular cells surrounding colloid mass
flat cuboidal epithelial cells
30
describe the hormonal release of thyroid hormones
TSH binds to receptor on surface of epithelial cells | GTP to GDP and cAMP to cause exocytosis of thyroid hormones into blood
31
how does T3 bring about physiological responses within cells
binds to receptor in target cells to form complex translocates to nucleus and binds to thyroid response elements on target genes to increase BMR and stimulates these genes
32
autoimmune thyroiditis causes
graves disease | hashimotos thyroiditis
33
what polymorphisms can cause dysregulated immune system to lead to autoimmune thyroiditis
CTLA-4 | PTPN-22
34
other causes of thyroiditis besides autoimmune
``` drugs dequervains palpation infection riedels subacute lymphocytic ```
35
causes of hyperthyroidism
``` 85% graves thyroiditis ectopic production factitious hyper-functioning nodules TSH secreting pituitary tumour carcinoma/adenoma ```
36
who is graves disease more common in
10x young middle aged women
37
pathophysiology of graves disease
antibodies to TSH receptor, thyroid peroxisomes and thyroglobulin act to stimulate receptor and increase gland function
38
causes of hypothyroidism
``` hashimotos thyroiditis iodine deficiency drugs post surgery congenital abnormalities inborn errors of metabolism secondary hypothalamic/pituitary pathology ```
39
what is hashimotos thyroiditis associated with genetically and demographically
10-20x women 45-60 other AA disease HLA-DR3 and HLA-DR5
40
describe the pathophysiology of hashimotos thyroiditis
anti-thyroid Ab - anti-thyroglobulin and anti-peroxidase | there is cell mediated cytotoxicity by CD8 t cells when Ab binds
41
how may hashimotos appear on histology
prominent lymphoid infiltrate | atrophy of follicles and progressive fibrosis
42
what is hashimotos at risk of and what raises suspicion of it
non-hodgkins B cell lymphoma | sudden enlargement of the gland
43
what may cause endemic diffuse goitre
goitrogenic substance | iodine deficiency
44
what may cause sporadic diffuse goitre
females more than males and young adults ingesting substances limiting T3/4 inborn error metabolism idiopathic
45
what mass effects may be seen due to goitre
airway destruction/compression dysphagia vessel compression cosmetic distress
46
how common is anaplastic thyroid cancer, who gets it, how does it appear
<5% older pt and hx of differentiated thyroid cancer undifferentiated, aggressive, rapid growth, involvement of neck structures death
47
what genetic and environmental factors may cause papillary carcinoma
MAP kinase pathway | ionising radiation
48
what genetic, demographic and environmental factors may cause follicular carcinoma
PI3K/AKT pathway iodine deficiency women 40-50s
49
what genetic factors may cause medullary thyroid cancer
MEN2
50
what genetic factors may cause anaplastic thyroid cancer
p53 and beta-catenin
51
presentation of papillary cancer
``` solitary nodule, multifocal, cystic, psammoma bodies lesion in thyroid or cervial node hoarse dysphagia cough SOB ```
52
spread of papillary cancer
late spread is usually lymphatic and can be haematogenous to lung but uncommon
53
overall survival rate for papillary thyroid cancer and what makes prognosis worse
>95% survival | worse in >40, extra thyroid extension or distal mets
54
presentation of follicular cell cancer of thyroid
single nodule, slowly enlarging, painless more solid more invasive
55
spread of follicular cell cancer?
haematogenous
56
mortality of widely invasive follicular cell cancer?
50% at 10y
57
mortality of locally invasive follicular cell cancer?
10% at 10y
58
where are medullary cancers of the thyroid derived from, who gets them
c cells sporadic, MEN in young pt or FHx in 40-50s sporadic MEN is a solitary nodule usually and FHx is often bilateral/multicentric c cell hyperplasia
59
what are the paraneoplastic syndromes of medullary cancer
diarrhoea due to VIP causing Cl secretion | cushings due to ACTH production
60
what are good prognostic factors for medullary cancer
young age and females | thyroid confined tumour with no mets
61
what are adverse prognostic factors in medullar cancer
necrosis, many mitoses, small cell morphology with <50% calcitonin +ve and type of RET mutation
62
management and recurrence of medullary cancer
total thyroidectomy | recurrence in 30%
63
who is hypothyroidism more common in
5-10x more women white populations older populations
64
goitrous causes hypothyroidism
``` hashimotos iodine deficiency drugs maternal transmission hereditary defects ```
65
non-goitrous causes hypothyroidism
atrophic thyroiditis developmental congenital issues post radiation post ablation
66
self limiting causes hypothyroidism
following ATx drugs postpartum thyroiditis subacute thyroiditis with transient hypothyroidism
67
secondary causes hypothyroidism
``` infection malignancy drugs trauma congenital cranial radiotherapy ```
68
what is hashimotos thyroiditis and whos more likely to have it
AA destruction of thyroid gland due to antibodies against thyroid peroxidase women, FHx of other AA disorders
69
hair and skin symptoms hypothyroidism
``` pale, clammy, doughy skin coarse and sparse hair periorbital puffiness vitiligo hypercarotenaemia dull nad expressionless face ```
70
cardiac symptoms hypothyroidism
low HR cardiac dilatation fluid retention leading to pitting oedema and pericardial effusion worsening HF
71
metabolic symptoms hypothyroidism
cold intolerance weight loss decreased appetite hyperlipidaemia
72
neuro symptoms hypothyroidism
``` depression/psychosis lowered intellectual/motor ability muscle stiffness peripheral muscle jerks carpal tunnel peripheral neuropathy encephalopathy prolonged tendon jerks decreased visual acuity ```
73
respiratory symptoms hypothyroidism
deep and hoarse voice macroglossia OSA
74
gynae symptoms hypothyroidism
menorrhagia oligo/amenorrhoea hyperprolactinaemia
75
GI symptoms hypothyroidism
constipation megacolon/obstruction ascites
76
biochemical features primary hypothyroidism
``` raised TSH and lowered FT3/4 raised prolactin raised CK raised LDL hyponatraemia macrocytosis +ve anti-TPO in hashimotos ```
77
management of hypothyroidism
50-100micrograms levothyroxine once daily morning before breakfast titrate with weekly bloods for 4 weeks then TSH 2m post dose change and 12m annual
78
what can impair levothyroxine uptake
food iron calcium PPI
79
true/false - in secondary hypithyroidism titrate levothyroxine to TSH
false - TSH is unreliable so do FT4
80
typical dose of levothyroxine to elderly pt with IHD
25-50 micrograms
81
who is more likely to have myxoedema coma
undiagnosed hypothyroidism or poor treatment complicance | elderly women with hypothyroidism long standing
82
features of myxoedema coma
bradycardia, prolonged QT, low voltage ECG complexes T2 resp failure with hypoxia/hypercarbia hypothermia respiratory acidosis adrenal failure 10%
83
management of myxoedema coma
``` ICU rewarm passively gradual increase dose levothyroxine hydrocortisone in adrenal failure broad spec ABx if needed cardiac monitor, monitor urine output, fluid balance, CVP, blood sugars and pulse ox ```
84
excess thyroid stimulation causes of hyperthyroidism
``` graves disease hashitoxicosis thyroid cancer choriacarcinoma thyrotropinoma ```
85
thyroid nodules with autonomous function causing hyperthyroidism
toxic solitary nodule | toxic multinodular goitre
86
thyroid inflammation causing hyperthyroidism
de quervains postpartum drug induced
87
exogenous thyroid hormones causing hyperthyroidism
over-treatment with levothyroxine | thyrotoxicosis factitia
88
ectopic thyroid tissue causing hyperthyroidism
metastatic thyroid carconoma | struma ovarii
89
cardiac symptoms thyrotoxicosis
AF palpitations increased HR heart failure
90
sympathetic symptoms thyrotoxicosis
tremor | sweating
91
CNS symptoms thyrotoxicosis
nervousness, irritability, sleep disturbance, anxiety
92
GI symptoms thyrotoxicosis
frequent loose bowel movements
93
metabolic symptoms thyrotoxicosis
heat intolerance increased appetite weight gain
94
hair, skin and msk symptoms thyrotoxicosis
proximal muscle weakness rapid fingernail growth thin and brittle hair
95
gynae symptoms thyrotoxicosis
lighter bleeds and less frequent periods
96
vision symptoms thyrotoxicosis
lid retraction double vision proptosis
97
signs of hyperthyroidism specific to graves
pretibial myxoedema thyroid acropachy thyroid bruit
98
investigating graves
decreased TSH and raised T3/4 hypercalaemia and raised Alk phos leucopenia TSH receptor Ab or anti-TPO but not as sensitive
99
whos more likely to have graves
females | 20-50
100
how many patients have graves eye disease and what is it associated with
20% graves pt | smoking
101
true/false - graves eye disease is always unilateral
false- but one eye is usually affected worse
102
mild graves eye disease management?
lubricants
103
moderate/severe graves eye disease management
steroids, radiotherapy, surgery
104
what may you see on investigation of nodular thyroid disease
``` asymmetric goitre raised T3/4 and low TSH Ab -ve high uptake on scinitgraphy thyroid USS ```
105
presentation of thyroid storm?
severe hyperthyroidism respiratory and cardiovascular collapse hyperthermia exaggerated reflexes
106
management of thyroid storm
``` ventilation if needed HDU/ICU propranolol except asthma then give rate limiting CCB fluids montitor glucocorticoids lugols iodine ```
107
first line management of thyrotoxicosis and how does it work
carbimazole once daily blocks TPO to block thyroid hormone synthesis
108
risk of carbimazole
aplasia cutis in early pregnancy
109
when is propylthiouracil first line and how does it work
1st trimester pregnancy | inhibits T4 to T3 by DIO1
110
risk of PTU AT drug
liver failure
111
general side effects of AT drugs
cholestatic jaundice increased liver enzymes FHF agranulocytosis
112
true/false - after episode of agranulocytosis AT drug can be used again
false
113
when is the risk of agranulocytosis highest
<6wks
114
when is radioidodine treatment contraindicated and what is the risk in graves
graves eye disease unless steroid cover, pregnancy | hypothyroidism in graves
115
risks to surgery for hyperthyroidism
recurrent laryngeal nerve hypothyroidism hypoparathyroidism
116
causes of thyroiditis
``` hashimotos dequervains drug induced post-partum radiation acute suppurative thyroiditis ```
117
who is de quervains thyroiditis more common in, symptoms and trigger
females and 20-50 viral infection neck tenderness, fever, self limiting
118
how does amiodarone cause thyroid issues
inhibits DIO1 so there is normal TSH but high FT4 and low FT3 hypothyroidism is more common but hyper can also occur
119
true/false - in a pt with pneumonia check thyroid function
false - theyre likely to have sick euthyroid syndrome
120
what is subclinical hypothyroidism, when to treat?
normal FT3/4 but high TSH higher risk in +ve TPO treat in pregnancy and if TSH >10
121
what is subclinical hyperthyroidism, what is it associated with and when is it treated
normal FT3/4 and low TSH multinodular goitre, AF, osteoporosis treat if TSH <0.1 or pre existing osteoporosis /AF

MB2: Endocrinology (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions