Thyroid Conditions Flashcards
What are thyroid function tests and what do they test for specifically?
These are tests used to diagnose and monitor thyroid disease. The tests test for thyroid stimulating hormone (TSH), T4, and T3, as well as related antibodies.
What is the ratio of T4 to T3 in the blood?
10:1.
How much more active is T3 than T4?
5x.
Describe the thyroid hormones.
T3 and T4 are the thyroid hormones, T4 is commonly referred to as thyroxine. They are both produced in the thyroid gland as a response to stimulation by TSH produced in the pituitary gland in the brain. They are essential for maintaining correct metabolism, defects of the thyroid hormones can be serious and life-threatening. Likewise, a total lack of thyroid hormones leads inevitably to death.
How are T3 and T4 related?
T4 is converted into T3 in the blood.
What is hyperthyroidism?
Hyperthyroidism is where the thyroid gland produces too much of the thyroid hormones. It can be characterised by a high concentration of T3 and T4, whilst a low concentration of TSH. This is because the thyroid hormones inhibit the production of TSH by acting upon the pituitary gland.
What is a common cause for hyperthyroidism?
This is commonly thought to be caused by an autoimmune disease known as Grave’s Disease.
What are the symptoms of hyperthyroidism?
Symptoms of hyperthyroidism include:
• Weight loss – despite a good appetite.
• Heat intolerance.
• Fatigue.
• Palpitations.
• Angina.
• Agitation.
• Goitre – swelling of the neck around the thyroid gland.
• Lid retraction – causing eyes to appear pushed forward, with a lot of the whites of the eyes visible.
• Oligomenorrhoea – infrequent menstrual periods.
What is the first line treatment for hyperthyroidism?
Carbimazole.
How does carbimazole work in hyperthyroidism?
It works by blocking the enzyme which converts tyrosine to thyroxine (thyroperoxidase), preventing the production of new thyroid hormones.
Why aren’t the clinical effects of carbimazole seen straight away?
The drug acts straight away but its clinical effects aren’t seen for a few days to weeks after the initial dose as the thyroid gland has a store of thyroid hormones that it must get through.
What dose of carbimazole is given initially? Why?
It is initially given at high doses to completely prevent thyroid hormone production until the patient becomes euthyroid.
What does the term euthyroid mean?
It is where the person produces no thyroid hormones.
After a person on carbimazole becomes euthyroid, how long are they maintained on the drug for?
If carbimazole treatment has worked for the patient and they have become euthyroid, they are usually kept on a lower maintenance dose for around 2 years.
If a patient who has been on carbimazole for two years can maintain euthyroid by themselves once the drug is removed then treatment with carbimazole isn’t continued. If no, what happens?
They are maintained on carbimazole indefinitely.
