The thyroid gland and hormones Flashcards
(103 cards)
1
Q
where is the thyroid located?
A
in the neck region on the anterior surface of the trachea
just below the larynx
2
Q
which hormone is most commonly used for hypothyroidism treatment?
A
T4
3
Q
define primary thyroid disease?
A
the pituitary produces more TSH as the thyroid gland isn’t responding
4
Q
define secondary thyroid disease?
A
disease in the pituitary
5
Q
what are secondary and tertiary thyroid disease usually accompanied by?
A
a whole other array of endocrine diseases
tertiary more than secondary
6
Q
what is tertiary thyroid disease?
A
at the level of the hypothalamus
7
Q
what is the most common type of hyperthyroidism and endocrine disorder?
A
primary hypothyroidism
8
Q
define primary hypothyroidism
A
decreased production of thyroid hormone at the level of the thyroid gland
9
Q
prevalence of primary hypothyroidism is ___%
A
2
10
Q
primary ht is more common in …..
A
women by 10-20 times
11
Q
causes of primary ht?
A
autoimmune disease
result of previous treatment for hyperthyroidism e.g. surgery
iodine imbalance
congenital hypothyroidism
12
Q
why is iodine imbalance uncommon in the uk?
A
as its in flour which is highly abundant
13
Q
what is congenital hypothyroidism?
A
born without a properly functioning thyroid or without a thyroid
14
Q
how are new borns tested for congenital hypothyroidism?
A
prick heel for blood after born to test for a variety of conditions
15
Q
hypothyroid patient symptoms are _____
A
unspecific
16
Q
examples of hypothyroid symptoms
A
lethargy dry skin sensitive to cold depression hair loss memory loss weight gain constipation puffy face
17
Q
how can you do thyroid function tests?
A
test for:
TSH
T4
thyroid peroxidase antibody- uncommon outside secondary care
18
Q
why is thyroid peroxidase antibody uncommonly tested for?
A
its expensive and you can test in other ways
19
Q
management of primary hypothyroidism in adults?
A
treat with lifelong T4
20
Q
how high does TSH need to be till you treat it with lifelong T4?
A
> 10mU/L
21
Q
how to treat is TSH is normal but you have low free T4?
A
LIFE LONG T4
22
Q
initial treatment to primary hypothyroidism in adults under 50?
A
initially 50-100mcg DAILY
adjusted: 25-50mcg every 3 weeks according to response
23
Q
initial treatment to primary hypothyroidism in adults over 50 and with heart disease?
A
initially 25mcg once daily
24
Q
why should you be careful with LS in patients with heart disease?
A
can increase HR if have too much
25
initial treatment to primary hypothyroidism in congenital hypothyroidism?
10-15mcg/kg
adjusted to 5mcg/kg
will keep taking forever
26
what is the maximum amount of LS you can give to a neonate
50mcg
27
when will treatment for congenital hypothyroidism start?
from about 6-7 days old
28
monitoring babies with congenital hypothyroidism
measure TSH after 8-12 weeks and then every 3 months after that until they're stabilised
29
what is the half life of T4?
7 days
30
adults maintenance dose?
100-200mcg DAILY
31
maintenance dose in children?
50-200mcg DEPENDING ON AGE
32
how often do you monitor TSH in adults
yearly
33
how often do you monitor TSH in children?
every 4-6 months until puberty
34
what levels of TSH do we aim for?
| what else do we aim for?
lower half of reference range 0.5-2
| symptom free
35
what might make you change an adults dose?
pregnancy
36
TF: there is benefit of using liothyronine and levothyroxine together over mono therapy?
FALSE- no evidence but a few did benefit
37
when is dual therapy used over mono therapy?
if unresponsive to mono therapy
| by specialist
38
what can be purchased on line for treatment of hypothyroidism?
desiccated animal thyroid gland
39
why isn't desiccated animal thyroid gland recommended
no evidence of benefit- no trials
| long terms effects are uncertain
40
patient advice for hypot
life long treatment
don't start at the same time as calcium or iron or caffeine as they can impact absorption
be careful with strengths as look similar
need for monitoring
entitled for medical exemption certificate
41
why is only a single daily dose needed?
has half life of a week
42
causes of hyperthyroidism?
graves disease
toxic nodules or cancer of the thyroid gland
antibodies to TSH receptor stimulate the gland
increased T3 and T4 production
43
what type of disease is graves disease?
autoimmune
44
prevalence of hyperthyroidism in women?
2%
| 0.2 in men
45
symptoms of hyperthyroidism?
```
anxious
palpitations
tremor
weight loss
tachycardia
goitre
heat intolerance
warm skin
diarrhoea
difficulty sleeping
```
46
what is goitre
| is it common
where the thyroid gland swells
| quite common but not all the time
47
what happens in primary hypothyroidism?
increased TSH to try stimulate the thyroid
| this means decreased unbound T4
48
What can you test for in hyperthyroidism?
TSH
| T4
49
What happens in primary hyperthyroidism?
decrease in TSH
as pituitary thinks there's a lot of T3 and T4 so no need to stimulate its production
T4 increase
50
why is there a low res of long term hypO thyroism with hyperthyroidism drug therapy?
as effects the production of T3 and T4 rather than affecting the gland itself
51
why does treatment for hyperthyroidism need monitoring?
rare but quite serious side effects
52
drug treatment uses for hyperthyroidism?
suppression or to block and replace
53
what is the most common drug used for hyperthyroidism.
carbimazole
| prodrug with methimazole as the active drug
54
when is drug therapy preferred for hyperthyroidism treatment
children
pregnant or breastfeeding
uncomplicated mild disease
55
mechanism of action for carbimazole?
interferes with thyroid hormone synthesis by inhibiting thyroperoxidase activity in follicular lumen of the thyroid itself
56
initial dose of carbimazole?
| then what?
15-40mg daily- depends on symptoms, can be higher
maintain until TFTs are normal and then reduce the dose to get balance with symptoms
maintain for 12-18 months
57
on carbimazole maintenance you decrease the dose by....
25-30% monthly
58
what happens if there's a hypert relapse after using carbimazole? how common is this
50% of patients
| longer term treatment required
59
what is the blocking replacement regimen?
give the patient hypothyroidism as its easier to manage
60
how do you achieve the blocking replacement regimen?
| duration
carbimazole 40-60mg for approx 4 weeks
THEN
carbimazole 40-60mg PLUS thyroxine 50-100mcg
for 18 months
61
what should happen after you stop the treatment for blocking replacement regimen?
thyroid gland should return to normal function
62
are people on blocking replacement regimen eligible for free prescriptions?
no as only made temporarily hypothyroid
63
why cant you do blocking replacement regimen in pregnant people?
carbimazole crosses the placental barrier, not enough T4.
| this knocks out their thyroid function with no replacement, born hypothyroid with severe developmental issues
64
what would happen if a pregnant women had hypertension?
carbimazole is only an issue if risks outweigh the benefits
| usually get propylthiouracil instead
65
dose of propylthiouracil?
200-400mg daily in divided doses
66
propylthiouracil maintenance dose?
50mg TDS
67
When is propylthiouracil needed?
pregnancy
| intolerant of carbazole
68
what can people who are intolerant to carbimazole get?
rash
| agranulocytosis
69
what is agranulocytosis?
a deficiency of granulocytes in the blood, causing increased vulnerability to infection
70
why is drug induced agranulocytosis an issue?
sudden onset
| cant predict it so you must give warnings to patients
71
carbimazole can cause _____ _____ ______
bone marrow supression
72
when should a full blood count be taken for patients on carbimazole?
if they get infection
73
carbimazole is a ____ daily dose
single
74
signs of agranulocytosis?
sore throat
mouth ulcers
bruising
75
TF: patients with hyperthyroidism are entitled to medical exemption certificate
FALSE
76
what would you do if a pateint on carbimazole comes int with a sore throat or mouth ulcers?
refer to GP immediately
77
advantages radioactive iodine treatment for hyperthyroidism?
non invasive
| excellent cure rate
78
disadvantages of radioactive iodine for hyperthyroidism
higher likelihood of long term hypothyroidism
can worsen eye disease- protruding eyes
avoid in pregnancy/ fatherhood
79
why does radioactive iodine have a higher risk of long term hypothyroidism
as radioactivity is taken up by the cells in the gland and will kill them
80
when is radioactive iodine used?
if failed to respond to drugs
relapse after drugs
comorbid heart disease
toxic nodular goitre- want to reduce quickly
81
advantages of surgery as a hypertension cure?
excellent and rapid cure rate
| good for goitre
82
disadvantages of surgery to treat hypertension
invasive
long term hypothyroidism
damage to parathyroid
scarring and swallowing difficulties
83
when is surgery preferred treatment for hyperthyroidism
oesophageal obstruction present
intolerance to drug treatment
young adults
84
why cant radioactive iodine or surgery be done straight after diagnosis?
as thyroid gland is a reservoir full of T3 and T4. If you start surgically messing around or killing the cells, you will get a huge spike of T3 and T4 in the body- Thyroid storm!
85
what must you do before giving radioactive iodine or surgery?
make patient euthyroid by using high doses of carbimazole so when you have the treatment the stores are depleted
86
what would happen in a thyroid storm?
Hyperpyrexia, dehydration.
Heart rate greater than 140 beats per minute, hypotension
Nausea, vomiting, diarrhoea, abdominal pain.
Confusion, agitation, delirium, psychosis, seizures or coma
87
what is adjuvant therapy for hyperthyroidism
betablockade
88
what does adjuvant therapy with beta blockers achieve?
palpitations, anxiety, tremor due to the high levels of T3 and T4.
89
how long is adjuvant therapy needed?
only at the start of treatments, once they start to come down you dont need to keep taking
90
why might you need higher doses of beta blockers in hyperthyroidism
as metabolism is increased
91
what drugs are likely to induce thyroid disease?
iodine
amiodarone
lithium
92
effect of iodine medication on the thyroid- when inducing thyroid disease?
acute: inhibits T3/4 release- hypothyroidism
prolonged: suppresses T3/4 production
rarely: thyrotoxicosis- if there is an underlying defect in autoregulation
93
why can iodine deficiency cause hypothyroidism?
due to inability to produce T3/4
94
How can iodine medication cause thyrotoxicosis?
if there is an underlying defect in autoregulation
95
what does amiodarone cause?
hypothyroidism
mild hyperthyroidism
severe hyperthyrodism
96
TF: when on treatment you still take amiodarone
TRUE
| usually stop in hypertension
97
How can amiodarone cause hypothyroidism?
| how would you treat this?
inhibition of T4 and T3 synthesis
| usually continue amiodarone and start T4 replacement therapy
98
how can amiodarone cause mild hyperthyroidism?
| what would you do about taking amiodarone?
blocks conversion of T4 to T3 which increases TSH and T4
| usually stop treatment with amiodarone
99
how can amiodarone cause severe hyperthyroidism
increased production of T4 because of iodine content
| direct thyroiditis- excessive release of T4 into circulation
100
what must be done if someone if on lithium?
monitor T3 and T4
101
how does lithium cause hypothyroidism?
| what would you do for treatment?
inhibits iodine uptake and prevents T3 and T4 release
monitor TSH
start T4 replacement IF SUBCLINICAL
102
what type of hypothyroidism can lithium cause?
subclinical or transient
103
can lithium cause hyperthyroidism?
yes
| rare, paradoxical effect
