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EndocrineJaz > Thyroid > Flashcards

Thyroid Flashcards

1
Q

vertebral level that thyroid sits at

A

C5-T1

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2
Q

thyroid sits infront of tracheal rings __+__

A

2nd-4th

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3
Q

thyoid increases in size physiologically in __/__

A

pregnancy

menstruation

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4
Q

innervation of the thyroid

A

parasympathetic from CNX

sympathetic from superior, middle and inferior ganglia of sympathetic trunk

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5
Q

blood supply of thyroid from

A

superior and inferior thyroid arteries (ECA)

+/- thyroidea ima

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6
Q

veins that drain from thyroid and where they drain to first

A

sup and middle thyroid - IJV

inferior - brachiocephalics

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7
Q

posteromedial aspect of thyroid is attached by ___ which the ___ travels near to/through

A

the Berry ligament

recurrent laryngeal n

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8
Q

tyrosine containing thyroglobulin filled spheres in thyroid

A

colloid

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9
Q

cells that line colloid in the thyroid

A

follicular cells

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10
Q

cells in thyroid that secret calcitonin

A

parafollicular C cells

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11
Q

synth and release of thyroid hormones:

___ from blood > ___ cells > ___ thyroglobulin>pinocytosis into ___ cell > lysosome > released into blood

A

I-
follicular cells
colloid
follicular cell

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12
Q

iodine attaches to ___ on thyroglobulin
1 = __
2 = __

A

tyrosine residues
MIT (monoiodotyrosine)
DIT

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13
Q

T3 is composed of __+__

A

MIT and DIT

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14
Q

T4 is composed of __

A

2x DIT

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15
Q

T3 and T4 are stored in

A

colloid thyroglobulin

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16
Q

__+___ prevent iodine from binding to form MIT and DIT

A

carbimazole and propylthiouracil

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17
Q

90% of thyroid hormon secreted is

A

T4

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18
Q

4x more potent thyroid hormone that is the major biologically active one

A

T3

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19
Q

T4 is converted to T3 by the __+__

A

liver kidney

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20
Q

TSH binds to a receptor on ___

A

follicular cell

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21
Q

T4 and T3 are ___ and so travel bound 70% to __, 20% ___, 5% to ___
inactive when bound

A

lipophilic
70 - TBG (thyroxine binding globulin)
20 - TBPA (thyroxine binding prealbumin)
5 - albumin

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22
Q

T3 bind __ less avidly to TBG and not significantly to TTR so

A

10-20x

more rapid onset/offset of action

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23
Q

conditions that can increase TBG levels (doesnt affect free T4 levels)

A 
pregnancy
neonate
OCP/oestrogens
tamoxifen
Hep A, biliary cirrhosis
porphyria
heroin
clofibrate
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24
Q

decreases level of TBG

A 
androgens
Cushing's - steroids
acromegaly
liver disease
nephrotic syndrome
phenytoin
carbamezepine
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25
The effects T4 and T3 that cause an increased BMR
increase no. and size of mitochondria increase O2 use and rate of ATP synth increase synth of resp chain enzymes
26
T4 and T3 __ thermogenesis, __ bg, ___ insulin dependent glucose uptake into cells, mobilise fat from ___, ___ FA oxidation, ___ protein synthesis
increase | adipose tissue
27
GHRH production and secretion requires ___ | slucocorticoid-induced GHRH release depends on __ and GH need __ presence for activity
Thyroid hormones
28
__+___ in foetal and neonatal brain requires thyroid hormones
myelinogenesis and axonal growth
29
thyroid hormones increase responsiveness to ___+___+__ by increasing __
adrenaline, noradrenaline, sympathetic NS neurotransmitters | increasing number of receptors
30
hypothalamus = __ > anterior pituitary = __ > thyroid =
TRH TSH T4+T3
31
in babies and young kids __ envnt stimulates TRH release
cold
32
circadian rhythm of thyroid hormones = increased at __ and decreased at __
up at night and down morning
33
___ enzymes activate and deactivate thyroid hormones by adding/removing I- from outer ring
delodinase
34
delodinase 2 function
activates T4 > T3 in tissues
35
Delodinase 1 is found in __+__
liver and kidney
36
delodinase 2 is found in (6)
``` heart skeletal muscle CNS fat thyroid pituitary ```
37
delodinase 3 is found in _+_+_
foetal tissue placenta brain (except pituitary)
38
2ndry hypothyroidism is/not associated with a goitre
isnt
39
s+s of hypothyroidism
``` slow relaxing reflexes lethargy weight gain cold intolerance decreased appetite slow pulse mentally sluggish ```
40
puffy face in hypothyroidism =
myxoedema
41
if hypothyroid in baby may cause ___
cretinism - dwarfism and mental retardation
42
auto anti body in Graves - | causes __thyroidism
TSI | hyperthyroidism
43
exophthalmos is caused by
water retaining carbohydrates building up behind the eye in Graves disease
44
s+s of hyperthyroidism
``` heat intolerance tremor palpitations nervous/v emotional lose weight increased appetite insomnia sweaty ```
45
in primary hyperthyroidism T4/3 = and TSH =
``` T4/3 = high TSH = low ```
46
in primary hypothyroidism T4/3 = and TSH =
``` T3/4 = low TSH = high ```
47
2ndry hyperthyroidism T4/3 = TSH =
both high
48
2ndry hypothyroidism T4/3 = TSH =
both low
49
subclinical hypothyroidism T4/3 = TSH =
``` TSH = high T4/3 = normal ```
50
myxoedema coma =
severe hypothyroidism
51
what is myxoedema?
accumulation of hydrophilic mucopolysaccharides in ground substance of dermis and other tissues > doughy induration of the skin (usually shins) seen in Graves
52
primary causes of goitrous primary hypothyroidism
Hashimoto's thyroiditis - AI iodine deficiency amiodarone lithium
53
non goitrous primary causes of hypothyroidism
congenital developmental defect, atrophic thyroiditis, post-ablative, postradiation
54
selflimiting causes of primary hypothyroidism =
after withdrawal of suppressive thyroid therapy, subacute thyroiditis, postpartum thyroiditis
55
2ndry causes of hypothyroidism
hypothalamic - encephalitis, sarcoid, malig | panhypopituitarism or isolated TSH deficiency
56
most common cause of hypothyroidism in Western world and in developing countries
``` western = hashimotos dev = iodine deficiency ```
57
Ig present in Hashimotos
TPO (thyroid peroxidase)
58
on microscopy of hashimotos =
T cell infiltrate and inflammation
59
fT4 is a better indication of hypothyroidism as __
there is preferential conversion to T3
60
``` s+s of hypothyroid: hair = face = periorbital ___ skin = hyper___ ```
``` coarse and sparse hair dull expressionless face periorbital puffiness pale cool doughy skin - maybe vitiligo and hypercarotenaemia hyperlipidaemia ```
61
gynae symptoms of hypothyroidism
menorrhagia > later = oligo/amennorhoea | hyperprolactinaemia as increased TRH causes increased PRL
62
other blood results for hypothyroidism other than hormones
macrocytosis increased CK and LDL hyponatraemia hyperprolactinaemia
63
starting dose of thyroxine in young and in elderly with HD
``` young = 50-100microg/day elderly = 25-50microg/day ```
64
TSH receptor Ig inGraves : Hashimotos % and its effect in both
``` Graves = 70-100% - stimulating Hashimotos = 10-20% - blocking ```
65
3 Igs in Graves and Hashimotos
anti TPO anti thyroglobulin TSH receptor
66
check TSH every __ after thyroxine dose change and ___ once stabilised
2mnths | 12-18mnths
67
in pregnancy dose of thyroxine =
can increase by 25-50% as TBG increased
68
if secondary hypothyroidism treated with levothyroxine then monitor __ not __
fT4 not TSH (as it stays low)
69
ECG and resp signs of myxoedema coma
bradycardia, low voltage complexes, heart block, T wave inversion, QT interval prolonged Type 2 resp failure - hypoxia, hypercarbia, resp acidosis
70
myxoedema coma is typically in
elderly F with longstanding but freq unrecognised and untreated hypothyroidism
71
Rx for myxoedema coma
``` ICU passively rewarm cardiac monitor fluids and electrolytes Abx broad spectrum thyroxine cautiously posssibly with hydrocortisone ```
72
``` hyperthyroidism s+s arrhythmia GI visual hair nail gynae muscles ```
AF diarrhoea chemosis, lid lag, lid retraction, diplopia, exophthalmus brittle thinning hair fast growing nails lighter periods and less frequent muscle weakness esp thighs and upper arms
73
causes of hyperthyroidism =
``` Graves multinodular goitre toxic nodule (adenoma) subacute/postpartum thyroiditis kelp amiodarone/lithium ```
74
Graves tends to fluctuate/stay constant | 50% __ at 18m and 50% __
fluctuate burn out relapse
75
graves goitre is ___
smooth and symmetrical
76
scintigraphy result in graves
diffuse increased uptake
77
Rx for grave eye disease
``` lubricants steroids short term inflam decrease radiotherapy Sx stop smoking ```
78
age range typical of graves and gender split
F2:1M | 20-50yo
79
demographic of nodular thyroid disease
older patient
80
nodular thyroid disease goitre -
asymmetrical
81
scintigraphy result for nodule thyroid disease goitre
patchy increased uptake
82
Signs of Thyroid storm
``` sever hyperthyroidism respiratory and CV collapse hyperthermia exaggerated reflexes need ventilation ```
83
Rx for thyroid storm
``` lugols iodine (stuns thyroid) steroids PTU beta blockers fluids and monitor ```
84
can cause agranulocytosis this drug can
carbimazole
85
hyperthyroid drug preferred in pregnancy
PTU
86
in Graves start carbimazole __ and __ over 12-18 months
high dose | taper
87
symptomatic control in hyperthyroidism =
beta blockers
88
if have had radioiodine what precautions must you take?
no close prolonged contact with kids/preg F dont share bed with partner for 2-3days avoid preg for 6 months ensure not preg
89
``` subacute thyroiditis aka F:M age range triggered by a phases ```
``` De Quervain's thyroiditis F>M 20-50yo virally hyper>hypo>eu ```
90
scintigraphy results for De Quervains thyroiditis
reduced uptake
91
2% of patients on amiodarone get __ 13% get ___ each more common if __ iodine intake
``` 2 = thyrotoxicosis - low iodine intake 13 = hypo - high iodine intake ```
92
thyroid embryology: | develops from evagination of ___ -descends through ___ along the ___
pharyngeal epithelium foramen caecum thyroglossal duct
93
embryology: if thyroid fails to descend =
lingual thyroid
94
if thyroid descends excessively =
retrosternal in mediastinum
95
can occur anywhere along the path of descent of the thyroid
thyroglossal duct cyst
96
the histology of cells that make up the thyroid
flat to cuboidal follicular epithelial cells
97
struma ovarii =
monodermal teratoma that is composed of thyroid tissue = ectopic production
98
on microscopy of graves =
scalloping and paling of colloid
99
HLA gene associated with Hashimoto's
HLA DR3+5
100
polymorphisms in these 2 immune regulation associated genes are a component of Hashimotos
``` CTLA 4 (-ve regulator of T cell responses) PTPN-22 (inhibits T cell function) ```
101
Hashimotos increases risk of __ and of developing ___ in affected gland
other AI conditions | B cell NHL
102
diffuse goitre - usual cause = F:M age eu/hyper/hypo?
idiopathic F>M young adults euthyroid usually - T3/4 normal but TSH increased/ULN
103
follicular adenoma description of its appearance =
discrete solitary mass - encapsulated by a collagen cuff
104
follicular adenoma are usually ___ but can lead to TSH independent ___
non-functional | thyrotoxicosis
105
__+___ mutations in a follicular adenoma can lead to it being functional
TSHR | G protein
106
Thyroid carcinomas: age, gender | 4 types
``` F>M, early adulthood papillary (75-85%) follicular (10-20%) medullary (5%) anaplastic (<5%) ```
107
5 causes of papillary thyroid carcinoma
``` ionising radiation active MAP kinase pathway rearrangements of RET/NTKR1 activating point mutation in BRAF ras mutation ```
108
the appearance of papillary thyroid carcinoma
usually solitary nodule, can be multifocal, often cystic | may be calcified = psammoma bodies
109
10 yr survival rate for papillary thyroid carcinoma
95%+
110
cause of follicular thyroid carcinoma (3)
iodine deficiency P13K/AKT pathway mutations ras (usually N-ras) mutations
111
age and gender of follicular thyroid carcinoma
F>M | 40-50yo
112
Describe follicular thyroid carcinoma
usually single nodule (slowly enlarging painless non-functional , may be part capsule, vascular/capsular invasion distinguishes it from adenoma)
113
spread of follicular thyroid carcinoma
not usually lymphatic - usually haematogenous
114
spread of papillary thyroid carcinoma
usually lymph nodes
115
mortality of follicular thyroid carcinoma at 10yrs
high stage = 50% | minimally invasive = >90%
116
medullary thyroid carcinoma marker =
calcitonin
117
MTC is associated with this genetic condition
MEN2 - germline RET mutations - can be very young patient
118
If familial then MTC =__/__
bilateral/multicentric
119
70% of MTC are sporadic and these usually develop at age ___ and are a ___
40-50yo | solitary nodule
120
MTC derived from ___
C cells
121
describe appearance of MTC -
spindle/polygonal cells in nests, trabeculae or follicles | associated with amyloid deposition (of calcitonin)
122
MTC are usually ___ and need a total ___
aggressive | thyroidectomy
123
paraneoplastic syndromes (2) associated with MTC
diarrhoea (VIP) | Cushing's (ACTH)
124
2 mutations associated with anaplastic thyroid carcinoma
p53 and beta catenin mutations
125
Anaplastic thyroid carcinoma: __+___ | age, in patients with a Hx of ____,
undifferentiated and aggressive older patient differentiated thyroid carcinoma
126
anaplastic thyroid carcinoma grows ___ and can involve ___
rapidly | other neck structures
127
Thy1 on FNA means
insufficient/uninterpretable
128
Thy2 on FNA means
benign
129
Thy3 on FNA means
atypia probably benign
130
Thy4 on FNA means
suspicion of malignancy
131
Thy 5 on FNA =
malignant
132
most differentiated thyroid cancers take up ___ and secrete ___ they are ___ driven
I- thyroglobulin TSH
133
factors associated with increased risk of differentiated thyroid cancers
``` Female (2/3:1M) not afro-caribbean radiation (strong link) increased TSH or parity thyroid adenomata ```
134
majority of differentiated thyroid cancers present with __ | some =
palpable nodules | chance finding on histology
135
differentiated thyroid cancers = __+__
follicular and papillary variants
136
commonest histological type of thyroid cancer (76%) =
papillary thyroid cancer
137
papillary thyroid cancer tends to spread via
lymphatics
138
thyroid cancer associated with Hashimotos
Papillary thyroid cancer
139
2nd commonest histological type of thyroid cancer (17%) =
follicular
140
follicular carcinoma of thyroid tends to spread via
haematogenous spread
141
incidence of follicular carcinoma is slightly increased in areas with ___
low iodine intake
142
Ix for differentiated thyroid cancers =
US FNA may involve an excision biopsy of lymph node if suspect vocal cord palsy = pre-op laryngoscopy
143
6 clinical predictors of malignancy in thyroid cancers
``` Male new nodule age <20 or >50 increasing size of nodule >4cm diameter Hx of head and neck irradiation vocal cord palsy ```
144
risk stratification used in post-op for thyroid cancers = ___ which stands for _+_+_+_
``` AMES age (older = worse) metastases extent size of primary tumour ```
145
Sx given to low risk AMES patients with differentiated thyroid cancers,<1cm papillary cancers and minimally invasive follicular ca with capsular invasion only
lobectomy with isthmusectomy
146
in differentiated thyroid cancer this is the Sx given if high risk AMES, extra thyroidal spread, multifocal, distant met.s, nodal involvement
sub/total thyroidectomy
147
if a patient with differentiated thyroid cancer has macroscopic lymph node disease Rx =
nodal clearance (Sx)
148
nodal clearance for papillary thyroid cancer with lymph node disease =
central compartment clearance and lateral lymph node sampling
149
nodal clearance for follicular thyroid cancer with lymph node disease =
central compartment clearance
150
check calcium within __ of thyroid Sx - replace if ___ and give IV if __/___
24hrs <2mmol/l <1.8/symptomatic
151
whole body iodine scan is done in patients who have had ___ usually ___ post-op stop T4 __ and T3 ___ before scan
sub/total thyroidectomy 3-6months T4 - 4wks T3 - 2 wks
152
senstitivy of iodine body scan is determined by ___
the elevation of TSH
153
long term affects of thyroid remnant ablation can be ___
small increase in AML incidence - mainly if cumulative I-131 doses >800mCi and repeated therapy does in 12months
154
thyroid remnant ablation process
pre treat with rhTSH > 2/3GBq I-131 capsules > discharge pt when <500cps at 1m count rate > usually give levothyroxine long term post this
155
rationale behind thyroid remnant ablation
to suppress TSH to <0.1mU/l and fT4 <25 ablate any microfoci in residual thyroid tissue and remove as source of Tg permit predictably useful scanning in whole body scane
156
C lymph node recurrence is more/less common in papillary over follicular thyroid cancer
more
157
___ is a tumour marker in diferentiated thyroid cancers
thyroglobulin
158
must measure ___ before thyroid remnant ablation because not everyone secretes it also measure ___ as can affect titre
thyroglobulin | anti-Tg Igs
159
if after Rx for differentiated thyroid cancer the Tg levels are rising but pt has a -ve whole body iodine scan what do you do?
possible PET scan to determine if Sx/radio appropriate + target specific tissue
160
S+S of congenital hypothyroidism
delayed jaundice poor feeding but "normal" wt gain skin and hair changes hypotonia (umbilical hernia, constipation)
161
screening test for congenital hypothyroidism = __ | done at day __
``` Guthrie test (TSH and fT4) 5 ```
162
s+s of hyperthyroidism in kids
``` behaviour problems sleep disturbance eating difficulties goitre fast HR precocious puberty ```
163
treatment for hyperthyroidism in kids
beta blocker carbimazole+/thyroxine for at least first 2 yrs then Sx/radio-iodine
164
causes of primary congenital hypothyroidism
gland dysplasia+/- abnormal site | inborn error of TH metabolism
165
4 factors that cause T4 to be converted to inactive rT3
stress fasting illness cortisol
166
3 thyroid autoIgs
antiTPO anti thyroglobulin TRAb
167
treatment of thyroid storm =
``` high dose carbimazole beta blockers hydrocortisone K+ iodide/lugol IV fluids +/- inotropes ```
168
one of the most common benign thyroid nodules =
colloid nodule
169
most penetrant feature of MEN2
MTC
170
MTC causes excess secretion of __ => present with___
calcitonin | diarrhoea
171
Rx for TMNG =
radio-iodine unless occupation is a contraindication
172
If have only taken carbimazole for few days before blood test (poor compliance) it will show =
normal fT4 but raised TSH as it has not had time to reduce yet
173
carbimazole is a very effective drug and so if it is not working it is usually due to ___
non-compliance
174
in hypopituitarism if give thyroxine before cortisol it may cause ___
Addison's crisis as it increases the BMR

EndocrineJaz (15 decks)

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