L08: Thyroid Disease Flashcards
What is the commonest hormone made in the thyroid gland
T4
What is the least common thyroid hormone
T3
What happens to t4
Becomes converted in the liver, kidney and thyroid into t3
What is the thyroid homeostasis
- Hypothalamus produced trh
- Trh acts on the pituitary gland to release tsh
- Tsh acts on the thyroid gland to produce t3 and t4
- When there is sufficient t3 and t4, this feedback negatively to the pituitary gland and hypothalamus to stop production of trh and tsh
What is primary hyperthyroidism
When there is high levels of t3 and t4, and low levels of tsh from the pituitary gland as it trying to decrease the amount
What is primary hypothyroidism
Low levels of t3 and t4 and high levels of tsh as its trying to stimulate the production of t3 and t4
What are the symptoms of primary hyperthyroidism
Nervousness Sweating Palpitations Weight loss Increased appetite Diarrhoea Eye signs
Everything in the body going fast
What are the causes of hyperthyroidism
Graves’ disease
Toxic Nodular goitre
Thyroiditis
Iodine induced
What investigations can be carried out in thyroid disease
Levels of free t3,4
TSH levels
Autoantibodies: thyroid peroxidase, TRAb (receptor antibodies)
What is Graves’ disease
An autoimmune disease that is common in females due to antibodies to tsh receptor thereby prevent tsh from doing its job
What are the 2 actions of antibodies
Stimulate the thyroid gland- hyperthyroidism
Inhibits the thyroid gland- hypothyroidism
What are the symptoms of Graves’ disease
Exophthalmos Dermopathy (skin changes) Diplopia Changes in vision Inability to close eyes
What is toxic Nodular goitre
- When there is an increased tsh drive which causes thyroid growth and formation of nodules
- The thyroid gland works on its own
- With time thyroid hormone increases
- In areas of thyroid deficiency, the thyroid is forced to make more t3 than t4 which results in t3 thyrotoxicosis
Where is toxic Nodular goitre common
In areas of iodine deficiency
What is the treatment of thyrotoxicosis
Destruction of thryoid tissue with radio iodine
Anti thyroid drugs e.g carbimazole
Surgical ablation
What is the treatment for Graves’ disease
Prolonged carbimazole
Radio iodine
In toxic Nodular goitre are there positive antibodies
No
What are the 2 main anti thyroid drugs
Carbimazole
Propylthiouracil
How do anti thyroid drugs work
Block the iodine uptake and organificaiton
When can beta blockers be used
For symptomatic release due to everything going too fast
What is the mechanism of action of radioactive iodine
Radioactive iodine gets taken up by the thyroid cells and causes follicular cell destruction
What are the complications of surgery
Hypothyroidism
Haemmorhage
Recurrent laryngeal nerve palsy
Hypocalcaemia
What is thyroditis
Temporary overactive thyroid gland
How is thyroditis diagnosed
History of pain
Family history
Thyroid function is fast and has no antibodies
Radionuclides scan shows no uptake into the thyroid
What is the treatment of thyroditis
Beta blockers: to relieve symptoms
Prednisolone (if very symptomatic)
What is post partum thyroditis
Thyroditis seen after pregnancy, usually common in underlying auto immune thyroid disease
What is the 2 phases seen in thyroditis
- Hyperthyroid phase
2. Hypothyroid phase
What is iodine induced thyrotoxicosis
when there is an idoine load there will be a drive in t3 and t4
What are the causes of hypothyroidism
Autoimmune disease:
- Hashimoto thyroiditis
- atrophic thyroiditis
Loss of functional tissue:
- post surgery or radio-iodine
Thyroiditis:
- Viral or post partum
Drugs
Hypopituitarism
What are the features of hypothyroidism
Fatigue, weakness, cold intolerance, weight grain, constipation Dry skin, edema, hoarseness Decreased hearing Myalgia Depression
Everything slowing down
What is hypothyrodism treated with
Levothyroxine
What is a goitre
Enlarged thyroid gland
What are the worries of goitre
New apperance Solitary nodule Recent changes to size and pain Male patient Mid line nodule Obstructive symptoms
What is the first line test for a goitre
Ultrasound
If the apperance of the goitre is u3 beyond what is the next step
Fine needle aspiration
What are the outcomes of fine needle aspiration
Papillary cancer
Colloid nodule
What is the management of thyroid cancer
Surgery
Radioactive iodine
Levothyroxine to suppress the tsh
What is non thryoidal illness
When people are sick they can have abnormal thyroid test i.e inhibition of t4 to t3 conversion to conserve energy
What is levothyroxine
A synthetic t4 hormone
What is the mechanism of action of carbamazole
Reducing the production of t3 and t4
What are the 3 main anti thyroid autoantibodies
Anti thyroid peroxidase (anti-too):
- hashimoto thyroditis
- graves
Tsh receptor antibodies:
90-100% Graves’ disease
Thyroglobulin:
70% of hashimoto thyroditis
30% Graves’ disease
What antibodies are common in hashimoto thyroditis
Anti thyroid peroxidase (TPO) and anti thyroglobulin
What is the long term prognosis of patients with Graves’ disease
Majority experience recurrent episodes in the future
10-20% experience full remission
Less than 10% experience hypothyroidism
What other condition is patient with Graves’ disease at risk of
Pernicious anaemia (another autoimmune condition)
What is the best treatment for Graves’ disease
Carbimazole, dosed on a reducing regimen over 18 months
