Thyroid Flashcards
Does thyroid disease affect men or women more?
Women
What is the single most common presentation of thyroid disease?
Goitre: thyroid gland enlargement
What is goitre?
Thyroid gland enlargement
What is hypothyroidism?
Low levels of thyroid hormones in the blood
What causes hypothyroidism?
Primary:
- autoimmune: Hashimoto’s + Atrophic
- drugs
- iodine deficiency
Secondary:
- problem with pituitary or hypothalamus
Clinical features of hypothyroidism?
Fatigue Weight gain COLD intolerance Bowels slow down Menorrhagia Mental slowness Oedema: periorbital and generalised Delayed reflexes
Investigations of thyroid disorders?
Check levels of TSH, T3, T4
Look for thyroid antibodies
Isotope uptake scan: the bright bits indicate an area of increased activity
What would you see on blood tests of primary hypothyroidism?
Raised TSH
Low T3 and T4
Anti-thyroid antibodies will be present if autoimmune cause
What would you see on blood tests of secondary hypothyroidism?
TSH is low
Low T3 and T4
Management of hypothyroidism?
Synthetic Levo-thyroxine
- doses depend on cause and size of person
Monitor the patient carefully on this drug
Which hypothyroidism patients should you NOT give L-thyroxine to? Why?
Patients with ischaemic heart disease, it can trigger angina and MI
What is autoimmune thyroiditis?
When the body creates antibodies against the thyroid and the hormones it produces (T3 +T4)
Damaging and impairing the function of the thyroid
Which autoimmune thyroiditides cause hypothyroidism?
Atrophic hypothyroidism
Hashimoto’s thyroiditis
Presentation of Hashimoto’s thyroiditis? Explain?
Hypothyroid symptoms
Goitre
Caused by lymphocytic and plasma cell infiltration of the thyroid
What is atrophic hypothyroidism?
Atrophy (no goitre)
Caused by lymphocytic infiltration of thyroid
What would autoimmune hypothyroidism look like histologically?
Many lymphocytes, small blue cells
Not many follicles seen and not much colloid
Which autoantibodies are commonly seen in autoimmune hypothyroidism?
Antibodies against:
- thyroglobulin
- thyroid peroxidase (anti-TPO) (an enzyme found in colloid)
Rarely: antibodies against TSH, will prevent TSH stimulating the thyroid to work
Does iodine deficiency cause hyper or hypothyroidism?
Hypothyroidism
What are the signs of iodine deficiency?
Massive goitre
What is hyperthyroidism?
Excess of thyroid hormones in the blood
What 3 mechanisms cause hyperthyroidism?
- Over production of thyroid hormones
- Leakage of pre-formed thyroid hormones
- Ingestion of excess thyroid hormone
Causes of hyperthyroidism?
Grave’s disease
Toxic multi-nodular goitre
Toxic adenoma
Drugs
Clinical features of hyperthyroidism?
Weight loss Tachycardia HEAT intolerance Increased bowel movements Lid lag and stare Menstrual slowing and stopping Anxiety Increased appetite Tremor
What would you see on blood tests of primary hyperthyroidism?
Raised T3 and T4, low TSH
What would you see on blood tests of secondary hyperthyroidism?
Raised T3 and T4, high TSH
What are some Grave’s disease specific clinical features?
Diffuse goitre
Thyroid eye disease
Pretibial myxoedema
Acropachy
What is pretibial myxoedema?
Waxy discolouration of skin
Peau d’orange
Of anterior lower legs, spreading to dorsum of feet
What is Arcopachy?
Swelling of hands and clubbing of fingers
Management of hyperthyroidism?
Anti-thyroid drugs
Radioiodine
Surgery to remove part or all of thyroid
Name the most common group of anti-thyroid drugs?
Name one?
How does it work?
Thionamides
Carbimazole
Reduces synthesis of new thyroid hormones
Doesn’t treat the underlying cause, however
Which hyperthyroidism patients tend to have worse prognoses?
Severe hyperthyroidism
Large goitre
Men more than women
Young at age of onset
What is a serious side effect of taking thionamides?
Precautions?
There is a high risk of agranulocytosis, this manifests as a sore throat, fever, mouth ulcers
It is very serious, you must warn patients to stop the drug if they get any of these symptoms
How does radioiodine work?
It is a radioactive isotope, which damages the thyroid, preventing it from functioning as well, reducing thyroid hormone levels
What is Grave’s disease?
An autoimmune condition that causes production of IgG antibodies that bind to the TSH receptor
This stimulates thyroid hormone production
Leading to hyperthyroidism
What is the name of the antibodies involved in Grave’s disease?
Thyroid stimulating antibodies
What would a thyroid affected by Grave’s disease look like histologically?
Hypertrophy of thyroid follicular cells
Less colloid
Pinker
List some risk factors for getting autoimmune thyroiditis?
Genetics, certain HLAs Environmental Female Postpartum Smoking, high iodine intake, stress
Which autoimmune disorders have strong associations with autoimmune thyroiditis?
Diabetes M type I
Pernicious anaemia
Coeliac disease
RA, SLE, Sjorgen’s
What is thyroid associated ophthalmopathy?
Swelling of intra-ocular muscles caused by an auto-antigen attacking them
Associated with autoimmune thyroiditis
Clinical features of thyroid associated ophthalmopathy?
Inflammation of eyes
Proptosis: bulging eye
Why does proptosis occur in thyroid associated ophthalmopathy?
Swelling of intra-ocular muscles makes the optic nerve, which is usually slack, become taut
The eye pushes forward and bulges out
Which drugs are associated with thyroid disorders?
Amiodarone: an ant-arrhythmic
Lithium: bi-polar disorder drug
What effect does amiodarone have on the thyroid?
Hyperthyroidism:
Because the pills contain a lot of iodine, meaning the person is ingesting more iodine than they need
Hypothyroidism:
Due to damage caused by iodine overload
How do you treat hyperthyroidism caused by amiodarone?
Stop amiodarone
If you can’t, consider steroids, anti-thyroid drugs
Surgery
How do you treat hypothyroidism caused by amiodarone?
Give thyroxine
No need to stop amiodarone
What effect does lithium have on the thyroid?
Causes hypothyroidism
Patient presents with puffy eyelids and bulging eyes, she has lost weight and gets hot and sweaty easily.
OE you see a diffuse goitre.
What does she likely have?
Hyperthyroidism
Caused by Grave’s disease
Patient presents with constipation, and complains he feels the cold far more than he used to. His wife has noticed he appears blank and stares a lot.
OE you see no goitre
What does he likely have?
Hypothyroidism
Caused by atrophic autoimmune disease
Patient presents with anxiety, more loose and frequent bowel movements and oedema on her face and legs.
She is known to be having treatment for atrial fibrillation.
What does she likely have?
Hyperthyroidism
Caused by amiodarone she is taking for her AF
Patient presents with weight gain, constipation and complains her periods have been particularly heavy and painful over the last few months.
What does she likely have?
Hypothyroidism
A new mum presents complaining of loose bowel movements, excess sweating and anxiety.
OE you see she has goitre
What does she likely have?
Hyperthyroidism
What is thyrotoxicosis?
High levels of thyroid hormones
(caused by anything, not just thyroid disease)
So its basically the same thing as hyperthyroidism
What is a thyroid storm?
Which thyroid diseases are at risk?
Precipitating factors?
An extreme manifestation of hyperthyroid due to overproduction of thyroid hormones
Graves, toxic adenoma, toxic multinodular goitre
Precipitated by surgical, trauma, childbirth, hypo, DKA, MI, drugs (amiodarone)
Clinical features of thyroid storm.
Tremor Tachycardia (+/- AF) Fever (over 41) Agitation, delirium, confusion Abdo pain, nausea and vomiting
Management of thyroid storm?
Resuscitate (IV fluids, oxygen)
Cool down: cold towels, paracetamol
Antithyroid treatment:
- Carbimazole
- Lugol’s solution (iodine)
- B blockers (propranolol)
- hydrocortisone
If no improvement:
- plasma exchange
- thyroidectomt
