Hyperthyroidism Flashcards
What is hyperthyroidism?
A condition in which there is overproduction of the thyroid hormone by the thyroid gland
This results in elevated levels of T3 and T4 and suppressed levels of TSH
What are the three general causes of hyperthyroidism?
Primary hyperthyroidism
Secondary hyperthyroidism
Thyrotoxicosis
What is primary hyperthyroidism?
It is hyperthyroidism resulting from a dysfunction within the thyroid gland
What are the three causes of primary hyperthyroidism?
Grave’s Disease
Toxic Multinodular Goitre
Toxic Adenoma
What is the most common cause of hyperthyroidism?
Grave’s disease
What is Grave’s disease?
It is an autoimmune condition in which TSH receptor antibodies are produced by the immune system and mimic the actions of TSH, thus stimulating the TSH receptors on the thyroid
What are the two risk factors of Grave’s disease?
Female Gender
Smoking
What are the four specific clinical features of Grave’s disease?
Exophthalmos
Ophthalmoplegia
Pretibial Myxoedema
Thyroid Acropachy
What is exophthalmos?
It is the term used to describe bulging of the eyeball out of the socket
What is pretibial myxoedema?
It is a dermatological condition in which there are deposits of mucin under the skin on the pre-tibial area
This results in shiny, orange-peel like skin on the shins
How does pretibial myoexedema present?
A discoloured, waxy, oedematous appearance to the skin over the pretibial area
What is thyroid acropachy?
It is a triad of finger clubbing, soft tissue swelling of the hands and feet and periosteal new bone formation
What goitre is associated with Grave’s disease?
Painless, smooth
What is another name for toxic multinodular goitre?
Plummer’s disease
What is the second most common cause of primary hyperthyroidism?
Toxic multinodular goitre
What is toxic multinodular goitre?
A condition in which multiple firm nodules develop on the thyroid gland that act independently of the normal feedback system and continuously produce excessive thyroid hormone
What goitre is associated with toxic multinodular goitre?
Rough
How does toxic multinodular goitre present on radioiodine uptake tests?
A patchy uptake
How do we manage hyperthyroidism related to toxic multinodular goitre?
Radioiodine therapy
What is toxic adenoma?
A singular nodule that grows on the thyroid gland causing it to become enlarged and produce excess thyroid hormones
How do we manage hyperthyroidism related to toxic adenoma?
The surgical removal of the nodule
What is secondary hyperthyroidism?
It is hyperthyroidism resulting from dysfunction within either the pituitary gland or the hypothalamus
This dysfunction results in an overstimulation of TSH
What is the cause of secondary hyperthyroidism?
Pituitary adenoma
What is a pituitary adenoma?
A singular nodule that grows on the pituitary gland
If this nodule secretes TSH, then hyperthyroidism can result
What is thyrotoxicosis?
it is is characterised by the clinical manifestations of inappropriately high thyroid hormone action in tissues
What are the three causes of thyrotoxicosis?
De Quervain’s Thyroiditis
Destructive Thyroiditis
Excessive Thyroxine Administration
What is another term for De Quervain’s thyroiditis?
Subacute thyroiditis
What is De Quervain’s thyroiditis?
A painful swelling of the thyroid gland thought to be triggered by a viral infection
De Quervain’s thyroiditis consists of how many phases?
Four
What is the first phase of De Quervain’s thyroiditis? How long does it last for?
It results in hyperthyroidism, painful goitre, raised ESR levels
3 - 6 weeks
What is the second phase of De Quervain’s thyroiditis? How long does it last for?
It results in euthyroid
1 - 3 weeks
What is the third phase of De Quervain’s thyroiditis? How long does it last for?
It results in hypothyroidism
Weeks to months
What is the fourth phase of De Quervain’s thyroiditis?
The thyroid structure and function goes back to normal
How does De Quervain’s thyroiditis present on radioactive uptake tests?
A globally reduced uptake of iodine-131
How do we manage hyperthyroidism related to De Quervain’s thyroiditis?
It is a self-limiting condition
Therefore, we simply prescribe NSAIDs for symptomatic relief
How do we manage severe hyperthyroidism related to De Quervain’s thyroiditis?
Corticosteroids
What is destructive thyroiditis?
It is a condition in which inflammation of the thyroid causes thyroid cell damage and destruction
This results in thyroid hormones stored in the gland leaking out and increasing thyroid hormone levels in the blood
What are the three causes of destructive thyroiditis?
Post-Partum
Viral Infections
Drugs
How do we manage post-partum related hyperthyroidism?
It is treated with beta blockers only - there is no need for anti-thyroid drugs due to the thyroid not being overactive
What drug is associated with destructive thyroiditis?
Amiodarone
What are the two classification of amiodarone induced hyperthyroidism?
Type One Amiodarone Induced Hyperthyroidism
Type Two Amiodarone Induced Hyperthyroidism
What is the pathophysiology of type one amiodarone induced hyperthyroidism?
It is caused by excess iodine induced thyroid hormone synthesis
Is goitre associated with type one amiodarone induced hyperthyroidism?
Yes
How do we manage type one amiodarone induced hyperthyroidism?
It is managed with carbimazole or potassium perchlorate
What is the pathophysiology of type two amiodarone induced hyperthyroidism?
It is caused by amiodarone related destructive thyroiditis
Is goitre associated with type two amiodarone induced hyperthyroidism?
No
How do we manage type two amiodarone induced hyperthyroidism?
Corticosteroids
What are the ten clinical features of hyperthyroidism?
Weight Loss
Heat Intolerance & Sweating
Anxiety
Tremor
Tachycardia
Palpitations
High Output Heart Failure
Diarrhoea
Oligomenorrhea
Amenorrhoea
What are the three investigations used to diagnose hyperthyroidism?
Bloods Tests
Radioiodine Uptake Test
Thyroid Ultrasound
What five blood test results indicate hyperthyroidism?
Increased T3 Levels
Increased T4 Levels
Decreased TSH Levels
TSH Receptor Stimulating Antibody Positive
Anti-Thyroid Peroxidase Antibody Positive
What is a radioiodine uptake test?
It involves the patient consuming a small dose of radioactive iodine and measuring the uptake by the thyroid gland
What radio iodine uptake test result indicates Grave’s disease?
A diffuse, homogenous, increased uptake
What is indicated when hyperthyroidism is associated with a decreased radioiodine uptake level?
Destructive thyroiditis
What is a feature of hyperthyroidism on ultrasound scans?
Thyroid nodules
What are the three pharmacological management options of hyperthyroidism?
Carbimazole
Propylthiouracil
Betablockers
What is the first line pharmacological management option of hyperthyroidism?
Carbimazole
What is the mechanism of action of carbimazole?
It blocks thyroid peroxidase from coupling and iodinating the tyrosine residues on thyroglobulin, thus reducing thyroid hormone production
What are the two side effects of carbimazole?
Agranulocytosis
Rash
What is agranulocytosis?
Decreased WCC levels
What advice should be given to individuals adminsitered carbimazole? Why?
They should attend for ugent medical review if they develop any features of infection
This is due to the side effect of agranulocytosis
What is the second line pharmacological management option of hyperthyroidism?
Propylthiouracil
When is propylthiouracil recommended to manage hyperthyroidism?
It is only recommended in pregnant patients and in those who are unable to tolerate carbimazole – due its risk of severe hepatic reactions
When are beta-blockers used to manage hyperthyroidism?
They are administered on initial diagnosis to relieve adrenalin-related clinical features – such as tachycardia, palpitations and tremor
Name a beta-blocker used to manage hyperthyroidism
Propanolol
What is the second line treatment option for hyperthyroidism?
Radioiodine treatment
What is radioactive iodine treatment?
It involves the patient consuming a small dose of radioactive iodine, which the thyroid gland then uptakes
This results in radiation emission, which destroys a portion of thyroid cells, leading to decreased thyroid hormone production
What do we do if patients are taking anti-thyroid medications prior to radioiodine treatment?
We advise individuals to stop the medication four to seven days before and after treatment
What is thyroidectomy?
It involves surgical removal of the whole thyroid gland or toxic nodules
What are the five complications of thyroidectomy?
Hypothyroidism
Hypocalcaemia
Hypoparathyroidism
Vocal Cord Damage
Confined Haematoma
In cases where hypocalacaemia develops following thyroid surgery, what is the feature present on ECG?
Isolated QTc elongation
How do we prevent complications arising during thyroidectomy?
They are prescribed potassium iodide before surgery
This decreases thyroid gland vascularity
What is a complication of hyperthyroidism?
Thyroid storm
What is another term for thyroid storm?
Thyrotoxic crisis
What is a thyroid storm?
It is a rare life-threatening complication of hyperthyroidism
When do thyroid storms usually present?
It usually presents in those with established thyrotoxicosis and is rarely seen as the presenting feature
What are the four causes of a thyroid storm?
Thyroid Surgery
Trauma
Infection
Acute Iodine Load
What are the seven clinical features of thyroid storm?
Fever > 38.5
Nausea & Vomiting
Tachycardia
Hypertension
Heart Failure
Jaundice
Confusion
What are the five management options of a thyroid storm?
Underlying Aetiology Management
Beta-Blockers
Anti-Thyroid Medications
Dexamethasone
Lugol’s Iodine
Name a beta blocker used to manage thyroid storms
IV propanolol
Name two anti-thyroid medications used to manage thyroid storms
Methimazole
Propylthiouracil
What dose of dexamethasone is used to manage thyroid storms?
IV 4mg
What is subclinical hyperthyroidism?
It is defined as a condition in which TSH levels are suppressed < 0.1 mu/l, however the free serum thyroxine and triiodothyronine levels are normal
What is the pathophysiology of subclinical hyperthyroidism?
The thyroxine hormone levels are at the upper range of normal, resulting in a decreased secretion of TSH to suppress this
What are the two causes of subclinical hyperthyroidism?
Multinodular Goitre
Excessive Thyroxine Administration
What is the conservative management option of subclinical hyperthyroidism?
We conduct TFTs everry 6 months
In cases where TSH levels stabilise and there are two similar measureemnts within the reference range 3 -6 months apart, TSH measurements can be stopped
What is the pharmacological management option of subclinical hyperthyroidism?
Low dose anti-thyroid medications for a period of six months
When is pharmacological management of hyperthyroidism recommended?
In cases where patients are symptomatic or present with goitre
What are the two complications of subclinical hyperthyroidism?
Osteoporosis
Atrial Fibrillation
