10-11-23 - Treatment of thyroid disorders Flashcards
Learning outcomes
- Understand the causes of hypothyroidism and hyperthyroidism
- Know how hypothyroidism is treated
- Know the treatment options for hyperthyroidism
- Understand the mechanism of action and side effects of directly acting anti-thyroid drugs
- Know the clinical uses of thyroid acting drugs
What are the 2 abnormalities of thyroid function?
What is T3 and T4?
- 2 abnormalities of thyroid function:
1) Hypothyroidism (‘underactive’ thyroid)
* Inadequate production and secretion of thyroid hormones (T3 and T4)
1) Hyperthyroidism (‘overactive’ thyroid)
* Excessive production and secretion of thyroid hormones (T3 and T4)
- T3 Triiodothyronine
- T4 Thyroxine
What are 5 Indications for performing thyroid function tests (TFT’s)?
- 5 Indications for performing thyroid function tests (TFT’s):
1) If there is a clinical suspicion of thyroid disease
2) Type 1 diabetes or other autoimmune diseases
3) New onset atrial fibrillation
4) In depression or unexplained anxiety
5) Weight changes
How well do thyroid conditions respond to treatment?
What is the aim of treatment?
Can patients feel fine with abnormal TFTs?
Why is treatment usually still recommended for asymptomatic patients with abnormal TFT’s?
What can symptom improvement lag behind?
- Thyroid conditions usually respond well to treatment
- The aim of treatment is to improve symptoms and return thyroid function to within or close to the reference range
- Patients may feel well even when their TFT’s are outside the reference range
- Treatment is usually still recommended for asymptomatic patients with abnormal TFT’s to reduce the risk of long-term complications
- Symptom improvement may lag behind treatment changes (this can take weeks to months)
How are hormones affected in hypothyroidism?
How common is it in the UK?
Which groups are more likely to be affected?
What are 3 Long term complications of hypothyroidism?
- Hypothyroidism
- Decreased serum free thyroxine (T4)
- Increased thyroid stimulating hormone (TSH)
- Found in approximately 2-5% of the UK population
- Females are 5-10 times more likely to be affected than males
- 3 Long term complications of hypothyroidism:
1) Cardiovascular disease
2) Goitre
3) Myxoedema coma (very rare but life-threatening condition)
* multiple organ abnormalities associated with altered sensorium
What is subclinical hypothyroidism?
How is it often detected?
What is its prevalence?
What are 3 Long term consequences of subclinical hypothyroidism?
- Subclinical hypothyroidism is a biochemical state where TSH is raised but T3 and T4 are within the reference range
- It is often detected incidentally although some people may experience symptoms
- Prevalence is 4-20% (proportion of a particular population found to be affected by a medical condition at a specific time)
- 3 Long term consequences of subclinical hypothyroidism:
1) Increased cardiovascular morbidity and mortality
2) Increased risk of fractures
3) Potential links to dementia
What are 9 symptoms of hypothyroidism?
- 9 symptoms of hypothyroidism:
1) Tiredness
2) Weight gain
3) Feeling cold
4) Constipation
5) Dry or thinning hair
6) Hoarse voice
7) Pins and needles
8) Low mood
9) Memory problems
What are 5 causes of hypothyroidism?
- 5 causes of hypothyroidism:
1) Autoimmune thyroiditis (Hashimoto’s)
* Most common cause
2) Congenital
3) Iatrogenic (e.g. post thyroidectomy or radio-iodine treatment)
4) Drug induced (e.g. anti-thyroid medications, lithium, amiodarone)
5) Pituitary disease
What is Hashimoto’s thyroiditis the most common cause of?
What type of disorder is Hashimoto’s thyroiditis?
What groups is it most common in?
- Hashimoto’s thyroiditis is the most common cause of hypothyroidism
- Hashimoto’s thyroiditis is an autoimmune disorder which results in the destruction of thyroid cells
- It is more common in females between ages 30-50
How common is Congenital hypothyroidism (CHT) in the UK?
What are 7 causes of CHT?
- 1 in 2000-3000 babies are born with CHT in the UK
- 7 causes of CHT:
1) Absent thyroid (agenesis)
2) Under-developed thyroid (dysgenesis) – more common in girls
3) Familial enzyme defects (dyshormonogenesis)
4) Iodine deficiency
5) Intake of goitrogens during pregnancy
6) Pituitary defects
7) Idiopathic
How can newborns with CHT present?
How are babies screened at birth for CHT?
What can untreated CHT lead to?
What can early treatment prevent?
- Newborns with CHT may have few or no clinical manifestations of thyroid deficiency
- All babies are screened at birth for CHT (heel prick test)
- Untreated CHT can result in impaired brain development and low IQ
- If treatment started before the baby is 2-3 weeks old the likelihood of significant long-term problems is low
What does amiodarone have a close structural resemblance to?
What can patients develop when taking amiodarone?
- Amiodarone has a very close structural resemblance to thyroid hormones
- Patients can develop amiodarone induced hypothyroidism or thyrotoxicosis therefore monitoring of TFT’s is important
What is the first line Treatment of primary hypothyroidism?
What is not offered?
- Levothyroxine (synthetic analogue of thyroxine) is first line treatment for primary hypothyroidism
- We do not routinely offer liothyronine for primary hypothyroidism due to lack of evidence
What is the starting dose of levothyroxine for <65 years old with primary hypothyroidism and no history of cardiovascular disease?
What is the starting dose of levothyroxine for >65 years old and adults with a history of cardiovascular disease?
What is the aim of this treatment?
How often should TSH be measured?
- Starting dose of levothyroxine for primary hypothyroidism is 1.6 micrograms/kg of body weight per day (rounded to the nearest 25 micrograms)
- For adults >65 years old and adults with a history of cardiovascular disease consider starting levothyroxine at 25-50 micrograms per day with titration as higher dose could exacerbate underlying cardiac disease
- Aim to maintain TSH levels within the reference range when treating primary hypothyroidism with levothyroxine
- Consider measuring TSH every 3 months until the level has stabilised ( 2 similar measurements within the reference range 3 months apart) and then once a year.
What is the treatment for subclinical hypothyroidism?
What is an exception to this?
- Subclinical hypothyroidism treatment:
- Recommendation is to consider levothyroxine in adults with TSH >10mU/L on 2 separate occasions 3 months apart
- Consider a six-month trial of levothyroxine for adults <65 years old with subclinical hypothyroidism who have:
- A TSH level above the reference range but <10 mU/L on two separate
occasions 3 months apart and who are experiencing symptoms of
hypothyroidism
How are hormones affected in hyperthyroidism?
What groups is it more common in?
- In hyperthyroidism, there is Raised T3 and T4 and low TSH
- It is more common in females that are 20-40 years olds (About 10 times more common in females than males)
What is the difference between thyrotoxicosis and hyperthyroidism?
How can we Differentiate between thyrotoxicosis with hyperthyroidism (eg Graves’ or toxic nodular disease) and thyrotoxicosis without hyperthyroidism (eg transient thyroiditis)?
- Hyperthyroidism is characterised by increased thyroid hormone synthesis and secretion from the thyroid gland, whereas thyrotoxicosis refers to the clinical syndrome of excess circulating thyroid hormones, irrespective of the source.
- We differentiate between thyrotoxicosis with hyperthyroidism (eg Graves’ or toxic nodular disease) and thyrotoxicosis without hyperthyroidism (eg transient thyroiditis) by:
1) Measuring TSH receptor antiboides (TRAbs) to confirm Graves’ disease
2) Consider technetium scanning of the thyroid gland if TRAbs negative
How is transient thyrotoxicosis without hyperthyroidism treated?
What should be given to hyperthyroidism patients who are waiting for specialist assessment and further treatment?
- Transient (temporary) thyrotoxicosis without hyperthyroidism (e.g from being unwell) usually only needs supportive treatment eg b-blockers, such as propanolol for tachycardia
- Consider antithyroid drugs along with supportive treatment for adults with hyperthyroidism who are waiting for specialist assessment and further treatment
What are 11 symptoms of hyperthyroidism?
- 11 symptoms of hyperthyroidism:
1) Anxiety
2) Palpitations
3) Weight loss
4) Goitre
5) Hair loss
6) Fatigue
7) Diarrhoea
8) Sweating
9) Muscle weakness
10) Insomnia
11) Periods lighter/infrequent
What are 7 causes of hyperthyroidism?
- 7 causes of hyperthyroidism:
1) Autoimmune – Graves’ disease (most common)
2) Toxic multinodular goitre – causes thyroid to work too much
3) de Quervain’s – (subacute) thyroiditis
4) Medication (overtreatment with levothyroxine)
5) Pituitary adenoma (tumour producing excess TSH)
6) Transient neonatal thyrotoxicosis (mother with Graves’)
7) Thyroid adenoma (rare)
What type of disorder is Graves’ disease?
What % of cases of thyrotoxicosis caused by hyperthyroidism does Graves’ account for?
How can Graves’ disease be confirmed?
What groups is it most common in?
What are 4 clinical features of Graves’ disease?
- Autoimmune disorder mediated by antibodies that behave like TSH
- Accounts for 60-80% of cases of thyrotoxicosis caused by hyperthyroidism
- Guidelines recommend measuring TSH receptor antibodies (TRAbs) in patients with thyrotoxicosis to confirm Graves’ disease
- Most common in women aged 30-60 years old
- 4 clinical features of Garves’ disease:
1) Diffuse goitre
2) Pretibial myxoedema
* Pretibial myxedema is a skin condition that causes plaques of thick, scaly skin and swelling of your lower legs
3) Thyroid eye disease (prominent eyes due to deposition of myxoedema behind the orbit)
4) Acropachy (swelling of distal digits with overgrown nail plates)
What is a toxic multinodular goitre?
How do cells in nodules differ from regular cells?
What is the most common cause of toxic multinodular goitre worldwide?
- Toxic multinodular goitres are small benign nodules within the thyroid gland.
- Cells within the nodules are unresponsive to secretory control mechanisms and secrete excess T3 and T4
- Worldwide, iodine deficiency is the most common cause
What is de Quervain’s (subacute thyroiditis)?
What is it triggered by?
What groups is it most common in?
- de Quervain’s (subacute thyroiditis) is painful swelling of the thyroid gland
- It is triggered by a viral infection
- Most commonly seen in women aged 20-50
What are 4 treatment options for hyperthyroidism?
- 4 treatment options for hyperthyroidism:
1) Radioactive iodine
2) Anti-thyroid medication
3) Symptomatic medication
4) Surgery - Important to discuss risks and benefits of all options with patients
