1
Q
What dose the thyroid gland produce?
A
- T3: Tri-iodothyronine
- T4: Throxine
2
Q
What is the thyroid gland essential for?
A
Growth, development and metabolism.
3
Q
How is T3 and T4 released from the thyroid gland?
A
- Hypothalamus releases Thyrotropin Releasing Hormone
- Acts on the anterior pituitary to release the Thyroid Stimulating Hormone
- Stimulates the thyroid gland to release T3 and T4
4
Q
Explain the negative feedback that occurs when a desired amount of T3 and T4 has been produced.
A
T3 and T4 cause the hypothalamus and anterior pituitary to reduce the amount of TRH and TSH produced.
5
Q
What are some effects of the thyroid hormones?
A
- Brain function
- Function of eye nerves and muscles
- Breathing rate
- Heart rate and function
- Liver function
- Function of digestive system
- Function of reproductive system
- Growth and Development
6
Q
What are the thyroid disorders?
A
- Hypothyroidism
- Hyperthyroidism
- Goitre
- Thyroid cancer
7
Q
What is hypothyroidism?
A
Insufficient T3 and T4 production
-> body can’t manage energy use
8
Q
What does the body try to do when a person has hypothyroidism?
A
Low levels of T4 -> Body tries to compensate by increasing levels of TSH -> Doesn’t increase T4 levels
9
Q
What is primary hypothyroidism?
A
Failure of the thyroid gland to produce thyroid hormones
10
Q
What can primary hypothyroidism be due to?
A
- Iodine deficiency
- Autoimmune thyroiditis
- Destruction of thyroid gland
- Drugs (amiodarone, lithium)
11
Q
What is secondary hypothyroidism?
A
Reduced production of TSH by the pituitary gland.
12
Q
What can secondary hypothyroidism be due to?
A
- Hypothalamic/pituitary dysfunction
- Tumour, trauma, surgery, radiotherapy
13
Q
What is overt hypothyroidism?
A
- Low levels of T4
- High levels of TSH
14
Q
Are patients symptomatic or asymptomatic in Overt hypothyroidism?
A
Symptomatic
15
Q
What is the aim of the treatment in overt hypothyroidism?
A
- Alleviate symptoms
- Get TFTs in normal range
16
Q
What is subclinical hypothyroidism?
A
- T4 in normal range
- High levels of TSH
17
Q
Are patients with subclinical hypothyroidism symptomatic or asymptomatic?
A
Asymptomatic
18
Q
Do subclinical hypothyroidism patients require treatment?
A
- Don’t usually require treatment
- If symptomatic -> Levothyroxine
19
Q
What are some complications of hypothyroidism?
A
- CV complication
-> CHD, HF - Reproductive
-> Fertility, Complication in pregnancy - Neurological
-> Deafness, concentration, memory, language - Myxoedema coma
20
Q
For the management of overt hypothyroidism, when would a patient be referred to the endocrinologist?
A
- Goitre
- Suspected Addison’s disease
- Pregnancy (planning)
- Cardio disease
- Atypical thyroid tests
- Drug causes
21
Q
What is first line for the treatment of overt hypothyroidism?
A
Levothyroxine
22
Q
What other drug can be given for the treatment of overt hypothyroidism?
A
Liothryonine
23
Q
What dose is given to patients on levothyroxine?
A
1.6mcg/kg/day (round to nearest 25mcg) for adults <65yrs
-> increase by 25-50mcg every 3-4 weeks
24
Q
What is the maintenance dose of levothyroxine?
A
100-200mcg
25
What is the lowest dose of levothyroxine given to patients with ischaemic heart disease or >60-65?
25-50mcg
26
What needs to be monitored in patients on Levothyroxine?
- Symptoms and TSH -> adjust/titrate dose
- LFTs every 3 months till TSH stable
-> 2 similar measurements 3 months apart
-> then annually
27
What are some adverse effects of Levothyroxine?
- GI disturbances
- CV - arrhythmias, tachycardia
- Fever
- Weight loss
- Muscle weakness
- Insomnia
28
What does levothyroxine interact with?
Calcium, antacids and iron salts
-> Take 4 hours apart
29
When should levothyroxine ideally be taken?
30 minutes before breakfast, caffeine containing liquids and other drugs
30
What is hyperthyroidism?
- Low levels of TSH
- High levels of T4
31
What are the causes of primary hyperthyroidism?
- Grave’s disease
- Toxic multinodular goitre
- Toxic thyroid nodule
- Drugs: amiodarone, lithium
32
What is Grave’s disease and how is it tested?
- Antibodies cause stimulation and secretion of thyroid hormones
- Test for TSH receptor antibodies
33
What can cause secondary hyperthyroidism?
TSH secreting pituitary tumour
34
What are some complications of Hyperthyroidism?
- CV - AF, increased risk of stroke
- Osteoporosis
- Eye disease -> vision loss
- Thyroid storm
35
What is thyroid storm?
Increased release of thyroid hormones -> worsening of symptoms
Medical emergency -> loss of conciousness
36
What are some signs and symptoms of hyperthyroidism?
- Hyperactivity
- Insomnia
- Palpitations
- Fatigue
- AF, HF
- Goitre
37
What are the 3 ways to manage hyperthyroidism?
- Surgery
- Radioiodine treatment
- Antithyroid drugs
38
Give 2 antithyroid drugs.
- Carbimazole
- Propylthiouracil
39
Explain the different ways antithyroid drugs may be taken.
Short term - prior to specialist review, surgery or radioiodine treatment
Medium term - Induce remission in Grave's disease
Long-term - Surgery or radioiodine treatment is contraindicated/declined
40
What is given to a patient with hyperthyroidism and they are experiencing tachycardia?
Beta blockers
41
If a patient has hyperthyroidism, what would be given as treatment for thyrotoxicosis?
Beta blocker e.g. propranolol
-> alongside anti-thyroid drugs
42
How is radioiodine treatment used in hyperthyroidism?
Damages DNA which cause death of thyroid cells
43
What do you have to make sure to do after radioiodine treatment?
Radioactive measures
- Avoid prolonged contact with children and pregnant women 3 weeks after treatment
44
What is radioiodine treatment contraindicated in?
- Active thyroid eye disease
- Pregnant women/breastfeeding
-> Women should avoid pregnancy 6 months after treatment
-> Men should avoid fathering children 4 months after treatment
45
What happens when radioiodine treatment is used in Grave's disease?
Can go from euthyroid to hypothyroid with 6 weeks to 6 months of treatment.
46
How do antithyroid drugs work in hyperthyroidism?
Reduces synthesis of thyroid hormone
-> Substrate binds to thyroid peroxidase - enzyme involved in thyroid hormones synthesis
47
What tests need to be done before a patient is put on an antithyroid drug?
- FBC
- LFTs
48
What is the risk of taking propylthiouracil for hyperthyroidism?
Small risk of severe liver injury.
49
When may propylthiouracil be taken for hyperthyroidism?
- Carbimazole is contraindicated
- Pregnancy (or planning)
- History of pancreatitis
50
When may a person require long term treatment of carbimazole/propylthiouracil?
- Severe hyperthyroidism
- Large Goitre
- Recent exposure to iodide
51
How are doses of carbimazole given?
High dose.
-> TFTs repeated. Dose adjustments if improvement
52
What are the 2 regimes for antithyroid drugs?
- Titration-block regime
- Block and replace regime
53
What is the titration-block regime of antithyroid drugs?
- Dose adjustment every 4-6 weeks
- Dose reduced if T4 levels fall -> hypothyroidism
- Want lowest dose that reaches euthyroidism
54
What is the block and replace regime of antithyroid drugs?
- Block thyroid hormone synthesis
- Monitor T4 and add levothyroxine till T4 in normal range
55
What are some side effects of carbimazole?
- Nausea
- Headaches
- Fever
- Malaise
56
What should a patient do if they are on carbimazole and have an itch/rash?
Treat with antihistamines
57
In what 2 conditions should a person stop carbimazole?
- Bone marrow suppression
- Jaundice
58
What is the normal dose of carbimazole?
15-40mg daily
59
What is the maintenance dose of carbimazole?
Low dose of 5-15mg
60
In what other case can carbimazole be given?
In the block and replace regimen
-> 40-60mg daily
61
What is an important condition where carbimazole must be stopped?
Neutropenia
-> Bone marrow suppression
62
What are some symptoms of neutropenia and what test should be done?
Infection - sore throat, fever
-> WBC count
63
What are the main side effects of propylthiouracil?
- Leucopenia
- Hepatic disorders: Hepatitis, Hepatic failure, Hepatic necrosis
64
What is the dose for propylthiouracil?
200-400mg daily
-> Maintenance till euthyroid, then dose reductions till maintenance dose
65
In what condition may require dose adjustments when on propylthiouracil?
Renal impairment
66
In pregnancy, if a patient is on levothyroxine, would they require a dose increase or decrease?
Increase
67
What 2 effects can amiodarone cause?
Hypothyroidism
-> Block conversion of T4 to T3
-> Increase in TSH
Hyperthyroidism
-> High iodine content
-> Excessive thyroid hormone production
68
What testing is done when a person is on amiodarone?
- LFTs before treatment: TSH, T3, T4, thyroid antibodies
- During: TSH, T3, T4
- After: TFTs as Long half life
69
What should you do if a person is on amiodarone and if hypothyroidism occurs?
Add levothyroxine and continue amiodarone
70
What happens when a person is on lithium and has hypothyroidism?
Inhibition of iodine uptake + thyroid hormone release
71
True or False: Lithium can cause hypothyroidism and hyperthyroidism.
True
72
Which monitoring is required for lithium and when is it done?
TFTs
-> Before and during treatment
73
Why are TFTs generally done for monitoring?
May be a suspicion of thyroid disorder
74
Which thyroid disorder is it if there is high levels of TSH and low levels of T4?
Hypothyroidism
75
Which thyroid disorder is it if there is low levels of TSH and high levels of T4?
Hyperthyroidism
76
Which thyroid disorder is it if there is high levels of TSH and T4 is within normal range?
Subclinical hypothyroidism
77
Which thyroid disorder is it if there is low levels of TSH and T4 is within normal range?
Subclinical hyperthyroidism
PHA332
flashcards
Decks in class (11)
# Cards
