Thyrotoxicosis and hyperthyroidism Flashcards
Are all cases of thyrotoxicosis associated with hyperthyroidism?
No, thyrotoxicosis is the result of increased thyroid hormone, but this excess thyroid hormone doesn’t always come from an overactive thyroid gland (Hyperthyroidism)
How can hyperthyroidism cause thyrotoxicosis?
- Excessive thyroid stimulation
- Autonomous thyroid nodules
What are some thyroid nodules that can become autonomous?
Toxic solitary nodule
Toxic multi-nodular goitre
What are some causes of excessive thyroid stimulation?
Grave’s disease
Hashitoxicosis
Thyrotropinoma (TSHoma)
Thyroid cancer
Choriocarcinoma
What are some non-hyperthyroid associated causes of thyrotoxicosis?
Thyroiditis
Exogenous thyroid hormones
Ectopic thyroid tissue
What are some causes of exogenous thyroid hormones in thyrotoxicosis?
Over-treatment with levothyroxine
Thyrotoxicosis factitia
What are some examples of ectopic thyroid tissue?
Metastatic thyroid carcinoma
Struma ovarii (Teratoma containing thyroid tissue)
What is Grave’s disease?
Grave’s disease is a type IIb autoimmune condition in which auto-antibodies bind to and activate TSH receptors, increasing T3 and T4 secretion
This causes hyperthyroidism
What is the most common cause of hyperthyroidism in younger patients (20-50)?
Grave’s disease
Describe the goitre formed in Grave’s disease
Smooth
What are the main symptoms in Grave’s disease?
- Hyperthyroidism with diffuse enlargement of the thyroid (Smooth goitre)
- Grave’s eye disease (Exophthalmos)
- Pre-tibial myxoedema
- Thyroid acropachy (Finger clubbing)
- Thyroid bruit (Associated with large goitres, reflective of hypervascularity of the thyroid)
What symptom of Grave’s disease is shown here?
Pre-tibial myxoedema
What is Grave’s eye disease?
A TRAb driven condition occurring in 20% of Grave’s patients, in which there is bulging of the eyes and lid retraction
What are some other names of Grave’s eye disease?
Thyroid eye disease (TED)
Grave’s opthalmopathy
What will blood testing show in Grave’s disease?
- Low TSH
- Raised fT4/3
- Hypercalcaemia and raised ALP (increased bone turnover)
- Leucopenia
- TSH receptor antibody (TRAb)
What is the most common antibody found in Grave’s disease?
TSH receptor antibody (TRAb) (70-100%)
What is the least common antibody found in Grave’s disease?
Anti-thyroglobulin (30-50%)
How will Grave’s disease be managed?
Mild disease is treated topically e.g. lubricants
Severe disease is treated with steroids, radiotherapy (Poor evidence) and surgery
What is the most common cause of primary hyperthyroidism in older patients (>50)?
Nodulatr thyroid disease
How will nodular thyroid disease present?
Insidious onset formation of asymmetrical goitre
What will testing show in nodular thyroid disease?
- Raised fT3/4
- Low TSH
- TRAb negative
- Scintigraphy shows high uptake (Iodine uptake scanning)
- Thyroid ultrasound
What are the main symptoms of thyrotoxicosis?
- Increased BMR
- Very fast pulse rate
- Increased nervousness and excessively emotional
- insomnia
- Sweating & heat intolerance
- Tendency to lose weight easily
- Tremors
- Muscle weakness
What are some cardiac symptoms of thyrotoxicosis?
Palpitations
Atrial fibrillation
What are some neurological symptoms of thyrotoxicosis?
Anxiety
Nervousness
Irritability
Sleep disturbance
What are some gastrointestinal symptoms of thyrotoxicosis?
Frequent, loose bowel movements
What are some visual symptoms of thyrotoxicosis?
- Lid retraction
- Double vision (Diplopia)
- Proptosis (Grave’s disease)
What are some hair and skin symptoms of thyrotoxicosis?
- Brittle, thin hair
- Rapid fingernail growth
What are some menstrual cycle changes that occur in thyrotoxicosis?
Lighter bleeding
Less frequent periods
What is a thyroid storm?
A medical emergency in which there is severe hyperthyroidism
What are some symptoms of thyroid storms?
- Respiratory or cardiac collapse
- Hyperthermia
- Exaggerated reflexes
Who is most at risk of thyroid storm?
Hyperthyroid patients, with an acute infection or recent thyroid surgery
How is thyroid storm managed?
- Lugol’s iodine
- Glucocorticoids
- PTU
- ß-blockers
- Fluids
- Monitoring
- Mechanical ventilation (If respiratory collapse)
What will blood detesting show in primary hyperthyroidism?
High fT3/4
Low TSH
What will blood testing show in secondary hypothyroidism?
High fT3/4
High TSH
How do anti-thyroid drugs?
They inhibit TPO, therefore blocking thyroid hormone synthesis
What are some examples of anti-thyroid drugs?
- Carbimazole
- Propylthiouracil (PTU)
What is the first line antithyroid drug in hyperthyroidism?
Carbimazole
How often is carbimazole taken?
Once daily
What can occur is carbimazole is taken during early pregnancy?
Aplasia cutis (Missing patches of skin on the babies scalp)
GI abnormalities
Choanal and oesophageal atresia
When is PTU used 1st line in hyperthyroidism?
In early pregnancy
How often is PTU taken?
Twice daily
What disease are PTU patients more at risk of?
Liver failure (1 in 10,000)
What are some possible side effects of anti-thyroid drugs?
- Rash, urticaria, arthralgia
- Cholestatic jaundice, raised liver enzymes
- Agranulocytosis
What is agranulocytosis?
Agranulocytosis is a lack of granulocytes in the blood, meaning the patient is at a high risk of infection
Can anti-thyroid drugs be used again after agranulocytosis occurs?
NO!
What is done to screen patients on anti-thyroid drugs for agranulocytosis?
Patients should be warned verbally, and in writing to stop the drug or to have urgent FBC checking in event of fever, ulcer or oropharyngeal infection
What are some management options of hyperthyroidism?
Anti-thyroid drugs
ß-Blockers
Radioiodine
Thyroidectomy
What is the use of ß-blockers in hyperthyroidism?
For immediate symptomatic relief of thyrotoxic symptoms due to its activity in reducing activity of the sympathetic nervous system
What is the main ß-blocker use din hyperthyroidism?
Propanolol
When is radio iodine used in hyperthyroidism?
relapsed Grave’s disease and nodular thyroid disease
When is radio iodine contraindicated?
It is contraindicated in pregnancy and is relatively contraindicated in active thyroid eye disease (Can be used with a steroid cover)
What is a possible complication of radio iodine usage in Grave’s disease?
High risk of hypothyroidism when used in Grave’s disease
When is thyroidectomy indicated in hyperthyroidism?
When radio iodine is contraindicated
What are some possible risks of thyroidectomy in hypertension?
Recurrent laryngeal nerve palsy
Hypothyroidism
Hyperparathyroidism
How does hCG affect the thyroid?
hCG causes stimulation of thyroxine release, which causes suppression of TSH
What are some symptoms of high hCG levels that help to distinguish it from hyperthyroidism?
- Hyperemesis gravidarum
- Not TRab antibody positive
- TSH low and not fully suppressed
- Resolves by 20 weeks gestation
When is gestational hCG-asscoiated thyrotoxicosis treated?
If it lasts longer than 20 weeks gestation
What can hyperthyroidism in pregnancy increase the risk of?
- Infertility
- Ammenorhoea
- Spontaneous miscarriage
- Stillbirth
- Thyroid crisis in labour
- Transient neonatal thyrotoxicosi
What are some possible causes of hyperthyroidism in pregnancy?
- Grave’s disease
- Toxic multinodular goitre
- Toxic adenoma
- Thyroiditis
How is hyperthyroidism usually managed in pregnancy?
Wait-and-see approach with supportive management given if necessary (ß-blockers)
If required, which low-dose antithyroid drugs given in pregnancy?
- Propylthiouracil 1st trimester
- Carbimazole 2/3rd trimester
What are soem possible side effects of propylthiouracil (PTU) in pregnancy?
Embryopathy
Liver toxicity
