Thyroid disease Flashcards
What do the thyroid hormones do
Increase metabolism of CHO, protein and fat
Increase O2 consumption
Synergistic with actions of catecholamines
What are the two types of goitres
Diffuse (spread over the neck)
Nodular (discrete area that is clearly different from surrounding thyroid gland
What is a goitre
Enlarged thyroid gland (non specific term for any enlargement of the thyroid gland)
When would diffuse goitres be formed
When there is over-stimulation of the thyroid gland by either TSH or TSI (Graves’ disease)
Different causes of hypothyroidism
- PRimary ofailure of thyroid gland (Hashimoto’s thyroiditis)
- Secondary to hypothalamic or anterior pituitary failure
- Lack of dietary iodine
- Drug induced
- Thyroid hormone resistance
What is Hashimoto’s thyroiditis and what are the plasma concentrations of hormones with this disease?
IS there a goitre present
Autoimmune disease of the thyroid
Low T3 and T4
High TSH
Goitre present
What are the plasma concentrations of hormones like in hypothyroidism caused. by hypothalamic or anterior pituitary failure?
IS there a goitre present
Low T3 and T4
Low TSH
No goitre
What are the plasma concentrations of hormones like in hypothyroidism caused by lack of dietary iodine
IS there a goitre present
Low T3 and T4
High TSH
Goitre present
Symptoms of hypothyroidism
Weight gain Dry skin Hoarse voice, slow speech Cold intolerance Constipation Lowered HR/BP Depression, confusion, poor memory
Some may get myxoedema- puffy appearance in face, hands and feet
Reduction in BMR and overall metabolic activity
How is BMR and metabolic activity like in hypothyroidism
Reduction in both
What is facial myxoedema
round, moon like
Puffy, pale, oedematous eye-lids
Thickened skin and dry
How are new-borns tested for cretinism
By testing for TSH and T4
How are primary and secondary hypothyroidism tested
Thyroid function test
Primary: low T3 and T4, high TSH
Secondary: Low T3 and T4, low TSH
If you suspect Hashimoyo’s what tests would you do
Test for thyroid antibodies
TPO, anti-thyroglobulin antibodies
What is the management of hypothyroidism
T4 (treatment of choice)
T3
How is T4 taken and what are the cautions
How to overcome these complications
Orally, once a day
- May worsen or uncover angina
- -> If angina, beta blocker is prescribed. Baseline ECG given with initial dosage
Why is T3 not routinely given for hypothyroidism? When is it used
Has a rapid onset and this can induce heart failure
Used in severe hypothyroid states when rapid response is desired (i.v.)
What are the causes of hyperthyroidism
- Abnormal levels of thyroid stimulating immunoglobulins (Graves’ disease)
- Secondary to excess hypothalamic or anterior pituitary secretion
- Hyper-secreting thyroid tumour
- Latrogenic causes
What are the plasma conc of hormones in hyperthyroidism caused by Graves’ disease and is. goitre present
High T3 and T4
Low TSH
Goitre present
What are the plasma conc of hormones in hyperthyroidism caused by secondary to excess hypothalamic or anterior pituitary secretion
High T3 and T4
High TSH
Goitre present
What are the plasma conc of hormones in hyperthyroidism caused by hyper-secreting thyroid tumour
High T3 and T4
Low TSH
Goitre present
What does TSI (thyroid stimulating immunoglobulins do )
Activate the thyroid gland (by binding to TSH receptors on thyroid gland) to produce and release thyroid hormones
What is the most common cause of hyperthyroidism
Graves’ disease
Classic signs and symptoms of Graves’ disease
Weight loss Sweating Heat intolerance Palpitations Tremor Nervousness Goitre Exophthalmos (bulging eyes)
symptoms of hyperthyroidism
Weight loss Sweating Heat intolerance Diarrhoea Palpitations Tremor Anxiety, emotional, irritable Restlessness
What is the increased cellular/tissue metabolism due to in hyperthyroidism
excessive thyroid hormone action
What is also enhanced in hyperthyroidism
Beta adrenoceptor responses
How to diagnose hyperthyroidism
primary - high T3 and T4, low TSH
Secondary- high T3 and T4, high TSH
If you suspect Graves’ disease, what tests do you do
Test for thyroid-stimulating antibodies
If you suspect thyroid tumours, what tests do you do
Thyroid uptake test using radioactive Iodine
what is the goal of treatment for hyperthyroidism
Euthyroid state and symptomatic relied from increased sympathetic activity
Management of hyperthyroidism
Anti-thyroid drugs
Radioiodine
Surgery
What are anti-thyroid drugs
Thionamides (carbimazole and propylthyiouracil(PTU))
What is the mode of action of anti-thyroid drugs
Decrease production of thyroid hormones by inhibiting iodination and coupling processes via TPO
-PTU also block T4 to T3 deionidation
HOw long do anti-thyroid drugs take to work
Several weeks because of colloid stores
What is the drug of choice for hyperthyroidism and what are the complications
Carbimazole but
-rashes and pruritis common
-Rare complication: neutropenia and agranulocytosis (bone marrow suppression) which are reversible
What drugs can be used to manage hyperthyroidism
Thionamides (anti-thyroid drugs)
Non-selective beta blockers
What is the action of non-selective beta blockers for managing hyperthyroidism and what they do
Reduce actions of catecholamines
-rapid symptomatic relief od tremor, palpitations, and anxiety
What are the two approaches used with anti-thyroid drugs
Dose titration- where only anti-thyroid drugs are used. Doses are adjusted to achieve normalisation of thyroid hormone production
Block and replace- where anti-thyroid drugs are given with thyroxine replacement
How do the two methods used with anti-thyroid drugs for hyperthyroidism compare
Both are equally effective
Dose titration method associated with a lower rate of side effects
When is radioactive iodine used and what is the possible complication
First line for older patients with nodular goitres and hyperthyroidism
Used when hyperthyroidism recurs after anti-thyroid drug therapy
-HYpothyroidism may result
When is thyroidectomy used (removal of some or all of thyroid)
What is the possible complication
When severe hyperthyroidism associated with a large goitre or concern about tumour development
Also used when there are obstructive symptoms
-Hypothyroidism may result
