Case 7 - Thyroid disease Flashcards
What are the types of hyperthyroidism?
Graves disease Thyroid tumour Post-partum hyperthyroidism Neonatal hyperthyroidism Abnormal thyroid stimulation Due to drugs
What is Graves’ disease?
Most common cause of hyperthyroidism
Autoimmune condition in which TSH-R Abs are made by the body
Stimulates the thyroid to produce more thyroid hormones
Has the characteristic eye signs of Graves’ disease and may produce a diffuse goitre
More likely to have other autoimmune conditions too
Normal or raised uptake on radioactive iodine scan
How can a benign thyroid tumour causes hyperthyroidism?
A small benign tumour can develop in the thyroid and become resistant to the negative feedback on the thyroid gland, and continues to make more thyroid hormones
How can tumours cause hyperthyroidism?
How can abnormal thyroid stimulation cause hyperthyroidism?
May produce a multinodular goitre
Usually in those >40y
Tumour of the thyrotrophic cells releases excess hormones
hCG particularly in pregnancy can mimic TSH and act at the receptors to stimulate the thyroid gland to produce thyroid hormones
How can drugs cause hyperthyroidism?
Interferons and amiodarone can cause it
What is post-partum hyperthyroidsim?
Sub-type of hashimotos Milder symptoms than in Graves' TPO Abs are made Decreased uptake of radioiodine Rarely requires treatment, just beta blockers for symptoms
What is neonatal hyperthyroidism?
When TSH Abs crosses the placenta to stimulate the fetus’ thyroid gland
What are the signs and symptoms of hyperthyroidism?
Anxious/Agitated Tachycardia Difficulty sleeping Tremor Intolerant to heat Hyperreflexia Conjunctival oedema Pretibial myxoema Proximal myopathy Acropachy Exophthalmos Omphthalmoplegia Weight loss
What are RFs for hyperthyroidism?
Female <40y Emotional/physical stress Smoker Pregnant Other autoimmune conditions FHx of thyroid disease
What are the treatment options for hyperthyroidism?
Beta blockers
Anti-thyroid drugs
Radioactive iodine
Thyroidectomy
What are the complications of hyperthyroidism?
Pregnancy - can lead to neonatal hyperthyroidism. Also pre-eclampsia, miscarriage, maternal HF
Arrythmias - AF can be caused by hyperthyroidism
Thyrotoxic crisis - rare and drastic, where a sudden increase in thyroid hormones leads to adrenergic symptoms
Osteoperosis
How do antithyroid drugs treat hyperthyroidism?
PTU or carbimazole
PTU take 3x a day, carbimazole once a day
Treat until T4 levels within range
Titrate dose down or block-replace (can’t do in pregnancy)
SEs- rash, itching, arthalgia, get pts to report infections as there’s a risk of agranulocytosis
How does radioactive iodine treat hyperthyroidism?
Taken as a drink
The iodine moves into the thyroid and reduces the activity of the cells by destroying them
Cannot sleep in the same bed as people, be around pregnant women or children etc. for significant periods of time
Eventually become hypothyroid
How does a thyroidectomy work?
Can be partial or total
Risks dependent on surgeon - can get recurrent laryngeal nerve damage
Will get subsequent hypothyroidism - need to take T4 post-op
Low relapse rate
How does the thyroid produce thyroid hormones?
Anterior pit gland makes TRH
TRH activates hypiothalamus to make TSH
TSH binds to G protein coupled receptor
Activates adenylyl cyclase to activate cAMP
Thyroglobulin made and secreted into colloid
Iodine moved into colloid using pendrin transporter
Combined with thyroglobulin using TPO
Thyroglobulin taken into cells
Broken down into T3 and T4
These are in circulation bound to thyroid binding hormones
Only free hormone can act on the tissues
T3 made 10x more by gland and is more effective at the tissues than T4 - T4 converted to T3 to act on cells
How can hypothyroidism be congenital?
Born with small/deformed/abnormally located or incomplete thyroid gland that cannot produce enough thyroid hormones
What is hashimotos thyroiditis?
Most common cause of primary hypothyroidism
Autoimmune condition where TPO Abs are made, leading to a lower production of thyroid hormones than usual
May cause a firm goitre
More common in women 40+
What is secondary hypothyroidism?
Sheehan’s syndrome - where infarct of the pituitary gland during hypovolaemia leads to a lower production of TRH and therefore lower production of thyroid hormones
Use T3/4 levels to monitor treatment
Other hormones are affected too
Check cortisol is within range to prevent Addisonian crisis
What are signs and symptoms of hypothyroidism?
Dry skin Thin hair Menorrhagia Cold intolerance Weight gain Constipation Muscle weakness/myalgia Hoarse/deep voice
What would TFTs show for hypothyroidism?
Primary = Low T3/4, High TSH Secondary = Low T3/4, Low TSH
What are the RFs for hypothyroidism?
Female <40y FHx of thyroid disease Other autoimmune conditions Antithyroid/radioiodine medications Thyroid surgery Radiation to neck/chest
What are the complications of hypothyroidism?
Birth defects
Heart problems due to increased cholesterol
Infertility
Myxedema - when the disease has progressed for a long time without treatment, the metabolism slows up to point where you can end up in a coma
How do you treat hypothyroidism?
Thyroxine
50 mcg in young, fit and otherwise healthy adults, 25 mcg in elderly
Titrate up until thyroxine levels are in the optimal range - 25mcg evry 4 weeks
Iron supplements will affect absorption
Only use statins if hypercholesterolaemia still present when thyroid hormones are in the correct range
What are the types of thyroid cancer?
Papillary - most common
In younger people
Women>men
Long survival
Follicular - more aggressive
Older women
Medullary - cancer of the C cells - will see a low level of calcium, as excess calcitonin is made
Strong link with hyperparathyroidism
Linked with other cancers
Anaplastic - hard to treat, aggressive
Lymphoma
What are red flag symptoms for thyroid cancer?
Growing lump Dysphagia Neck pain Hoarseness Hx of neck radiation FHx of thyroid Ca
How do you differentiate between a benign and malignant thyroid lump?
Age of patient Length lump has been there Iodine status Radiation exposure Thyroid status Diffuse vs. solitary nodule Pressure symptoms - tethering, laryngeal nerve palsy, mobility on swallowing
What investigations should you do for thyroid cancer?
US guided FNA
Can then take sample to cytology
Thy1 - Non-diagnostic Thy 2- benign - retest in 6 months Thy 3 - indeterminable Thy4 - Suspicious of malignancy Thy5 - Malignant
How do you treat thyroid cancer?
Thryoidectomy/lobectomy
Radioactive iodine
Anti-thyroid drugs- suppress TSH so growth not stimulated
