1: Hyperthyroidism, hypothyroidism and thyroiditis Flashcards
Thyroid disease can be ___ or ___.
primary , secondary
What is a goitre?
Lump in the thyroid gland
Primary thyroid disease is usually ___.
autoimmune
Secondary thyroid disease is usually caused by disease of which glands?
Hypothalamus
Pituitary gland
Which hormone is released from the anterior pituitary gland and affects the function of the thyroid gland?
Thyroid stimulating hormone (TSH)
also known as thyrotropin
TSH is also known as ___.
Thyrotropin
What are the two hormones produced by the thyroid gland?
T3
T4
“thyroxines”
99% of T3 and T4 is bound to what?
Transport proteins
Thyroxine binding globulin
Albumin
Pre-albumin
Which hormone, produced by the hypothalamus, triggers the anterior pituitary’s production of TSH?
Thyrotropin releasing hormone (TRH)
The hypothalamic-pituitary-thyroid axis is controlled by ___ feedback.
negative feedback
What happen to the levels of free T3/T4 and TSH in
a) primary hypothyroidism
b) primary hyperthyroidism?
a) Primary hypothyroidism - free T3/4 LOW, TSH HIGH
b) Free T3/4 HIGH, TSH LOW
In secondary hypothyroidism, is TSH raised?
No
Secondary hyperthyroidism is very rare. What are the levels of T3/4 and TSH?
Everything is high
What is hypothyroidism?
Insufficient secretion of thyroid hormones
What is severe hypothyroidism also known as?
Myxoedema
What is a rare sign of Graves disease, which itself causes hyperthyroidism?
Pretibial myxoedema
Hypothyroidism is very (common / uncommon).
common
Reduced intake of what can cause hypothyroidism?
Iodine
Hypothyroidism is categorised by the presence or absence of a…
goitre
What is an autoimmune cause of hypothyroidism which presents with a goitre?
Hashimoto’s thyroiditis
What occurs in Hashimoto’s thyroiditis?
Auotimmune destruction of thyroid gland
Reduced thyroid hormone secretion
Hashiomoto’s thyroiditis is more common in (men / women).
women
As with all autoimmune disease
What antibodies are seen in Hashimoto’s disease?
Thyroid peroxidase antibodies (TPO)
What is seen histologically in Hashimoto’s disease?
T cell infiltration
Why are the symptoms of thyroid disease so diverse?
Systemic impact of hormones
What is seen in the hair and skin of someone with hypothyroidism?
Coarse, sparse hair
Expressionless, puffy face
Pale, cold skin
Vitiligo
Hypercarotenaemia (orange skin)
People with hypothyroidism will complain of being very (hot / cold).
cold
What is seen in the ankles of people with hypothyroidism?
Pitting oedema
What are some cardiovascular complications of hypothyroidism?
Bradycardia
Cardiac dilatation
Effusions
Hyperlipidaemia (inc. xanthelasma)
People with hypothyroidism have a REDUCED appetite - what happens to their weight?
They gain weight anyway
Which systems does hypothyroidism also affect?
GI
Resp
Neuro
In primary hypothyroidism, you see (high / low) levels of TSH and (high / low) levels of T3/4.
high TSH (body trying to compensate)
low thyroid hormones
Which autoantibodies are raised in
a) Autoimmune hypothyroidism in general (Hashimoto’s)
b) Graves disease?
Hashimoto’s - anti-TPO
Graves - TSH receptor
How is hypothyroidism managed?
Levothyroxine tablets
25-100 µg
In primary hypothyroidism, levothyroxine dose is tailored to the levels of what?
TSH
What is levothyroxine also known as?
T4
When should patients take their levothyroxine?
Before breakfast
Why is levothyroxine taken before breakfast?
Food, drugs affect its absorption
e.g PPIs
Pregnant women require (higher / lower) doses of levothyroxine.
higher
What is an emergency associated with untreated hypothyroidism?
Myxoedema coma
Myoxedema coma is seen in ___ patients with untreated hypothyroidism.
How do they present?
elderly
Bradycardia, heart block
Respiratory failure
What is
a) hyperthyroidism
b) thyrotoxicosis?
Hyperthyroidism - overproduction of thyroid hormones by thyroid gland
Thyrotoxicosis - state caused by excess thyroid hormone
What does thyrotoxicosis look like?
Cardiac symptoms - palpitations, AF
Tremor
Sweating
Anxiety, nervous, irritable, insomnia
How do the bowel movements change in thyrotoxicosis?
Frequent, loose stools
What is a distinct facial presentation of thyrotoxicosis?
Lid retraction
Double vision
Bulging eyes (proptosis)
What is the most common cause of thyrotoxicosis?
Hyperthyroidism caused by Graves disease
Apart from Graves disease, what else causes hyperthyroidism?
Thyroid nodules
act independently, don’t respond to hypothalamic / pituitary axis and are toxic
Not all thyrotoxicosis is caused by hyperthyroidism. What else can cause it?
Thyroiditis - de Quervain’s, post-partum and drug-induced (e.g amiodarone)
Levothyroxine overdose - thyrotoxicosis factitia
Ectopic thyroid tissue i.e metastasis of thyroid cancer
Graves disease causes (hyper / hypo)thyroidism and is more common in (men / women).
hyperthyroidism
women
What lifestyle factor is thought to be involved in the onset of Graves disease?
Smoking
In Graves disease, what changes are seen in
a) TSH
b) T3/4 levels?
a) TSH decreases (to compensate for hyperthyroidism)
b) T3/4 increases (overproduction)
What bone issues are seen in Graves disease?
Osteoporosis
so hypercalcaemia and increased ALP
What antibody is raised in Graves disease?
TSH receptor antibody
note that it’s not an AUTOANTIBODY - stimulates cells rather than getting them destroyed
What is a rare sign of early Graves disease?
Pre-tibial myxoedema (which is confusing bc myxoedema means hypothyroidism)
What general sign is sometimes seen in Graves disease?
Specific type of finger clubbing called THYROID ACROPACHY
What can sometimes be heard on auscultation of a thyroid of someone with Graves disease?
Bruit
Graves disease causes serious ___ disease.
eye
Apart from Graves disease, what other thyroid disease can cause thyrotoxicosis?
Nodular thyroid disease
What does the goitre look like in
a) Graves disease
b) Nodular thyroid disease?
a) Grave’s goitre is symmetrical and smooth
b) Nodular goitres are… nodular and asymmetrical
What does a thyroid function test look like in nodular thyroid disease?
TSH decreases
T3/4 increases
Are people with nodular thyroid disease positive for TSH receptor antibody?
No
What is an emergency which can occur in people with untreated hyperthyroidism?
Thyroid storm
What does thyroid storm present as?
Respiratory and cardiac collapse
Hyperthermia
How is thyroid storm treated?
Cooling
Inhibition of thyroid gland with potassium iodide
Beta blockers to control sympathetic symptoms
How is hyperthyroidism treated?
Antithyroid drugs
What is an example of an antithyroid drug?
Carbimazole
What are some side effects of antithyroid drugs?
Skin reactions
Liver disease
AGRANULOCYTOSIS - neutrophils cannot produce granules to fight infection
What is the presentation of agranulocytosis?
Fever
Infection of mouth and throat
If patients develop agranulocytosis after taking an antithyroid drug, can they start using them again?
No
Which beta blocker is used in people with hyperthyroidism?
Propranolol
What is a possible side effect of propranolol?
Bronchospasm in patients with asthma
If a patient’s asthma worsened after taking propranolol for their hyperthyroidism, what would you give them instead?
CCB e.g diltiazem
If a patient’s Graves disease / nodular thyroid disease relapses after stopping drugs, what would you try instead?
Radioiodine
Can radioiodine be given to pregnant women?
No
What do patients have to be advised about if they are on radioiodine?
Contact with other people - their necks are radioactive
If both drugs and radioiodine have failed in patients with hyperthyroidism, what can be done?
Surgery
What are some complications of thyroidectomy?
Hypothyroidism
Hypoparathyroidism
Damage to recurrent laryngeal nerves (revise)
