Hyperthyroidism Flashcards
What is Graves’ disease?
Autoimmune
Antibodies bind to and stimulate TSH receptor in the thyroid
Cause goitre and hyperthyroidism
What symptoms can be seen because of the antibodies in graves?
Symptoms due to high BMR, goitre and exophthalmos * due to antibody
And another antibody can cause pretibial myxoedema
What happens if you give radio iodine = to a gravies pX?
Whole gland will absorbed iodine due to activity and whole will be seen
What is Plummer’s disease? ( Toxic Nodular goitre )
Not autoimmune
Benign adenoma that is overactive at making thyroxine
What are the differences between graves’ and toxic nodular goitre disease?
No antibodies in plummers so not pretibial myeoxma and exophaaltus
What will Toxic Nodular look like on iodine scan?
Not a uniform scan, one part where the benign part is. Not very active
What are the effects of thyroxine on the sympathetic nervous system?
Sensitises beta adrenoceptors to ambient levels of adrenaline and noraadrenaline
–> apparent sympathetic activation
–> tachycardia, palpitations, tremor in hands, lid lag
What are the symptoms of hyperthyroidism?
Weight loss despite increased appetite Breathlessness, palpitations, tachycardia Sweating Heat intolerance Diarrhoea Lid lag and other sympathetic features
What is a thyroid storm? (thyrotoxic crisis)
- Medical emergency : 50% mortality if untreated
- Blood results confirm hyperthyroidism
- Hyperpyrexia (>41)
- tachycardia/arrhythmia
- Cardiac failure
- Delirium/frank psychosis
- Hepatocellular dysfunction; jaundice
Any 2+ = thyroid storm
What are the treatment options?
Thyroidectomy ( surgery )
Drugs
What are the classes of drugs used in the treatment of hyperthyroidism?
- > Thionamides - Block the enzyme to make thyroxine ( propylthiouracil (PTU) carbimazole (CBZ)
- > Potassium Iodide
- > Radioiodine
- > B-blockers ( stop sympathetic symptoms )
- First 3 drugs reduce thyroid hormone synthesis
b blockers help with symptoms
What are the unwanted actions of thionamides?
Agranulocytosis (usually reduction in neutrophils) - rare and reversible on withdrawal of drug.
rashes (relatively common)
What is the role of B blockers in thyrotoxicosis?
Several weeks for ATDs to have clinical effects eg reduced tremor, slower heart rate, less anxiety
SO we used B blocker 1st:
NON-selective (ie b1 & b2) b blocker
eg propranolol
achieves these effects in the interim
How to prepare patients for surgery?
Excess KI to inhibit thyroid hormone synthesis and secretion
- short term only until surgery to control blood loss and size of gland
What are the risks with surgery?
Risk of voice change
Risk of also losing parathyroid glands
Scar
Anaesthetic
