Hyperthyroidism and Hypothyroidism Flashcards
What is thyrotoxicosis
Same as hyperthyroidism
Differentiate between primary and secondary hyperthyroidism
Primary = Pathology in the thyroid gland → excessive T3/T4 production.
Secondary = Pathology in the pituitary gland → excessive TSH release → excessive T3/T4
Signs and symptoms of hyperthyroidism
Anxiety and irritability
Tachycardia
Loose stools
Weight loss
Sweating
Heat intolerance
Insomnia
Overactive reflexes
Causes of hyperthyroidism
Mnemonic: G.I.S.T
Graves Disease
Inflammation (Thyroiditis)
Solitary toxic thyroid nodule
Toxic multinodular goitre
What is the most common cause of hyperthyroidism?
Graves’ Disease
Investigations for hyperthyroidism?
Physical Exam: Warm skin, hyperreflexia, tachycardia, goitre, eye signs, pretibial myxoedema.
Blood Tests: T3/T4, TSH, thyroid antibody screen (for Graves).
Thyroid ultrasound:
Diffuse increased uptake → Graves’
Single area of uptake → Solitary toxic nodule
Patchy uptake → Multinodular goitre
Absent/decreased uptake → Thyroiditis
First-line management of hyperthyroidism?
Carbimazole (anti-thyroid drug) for 12-18 months, then monitor TFT’s until normal
Alternative treatment for hyperthyroidism in pregnancy? What is a side effect of this drug?
Propylthiouracil (risk of severe liver reactions).
Role of radioactive iodine in hyperthyroidism?
Given as a single dose → Destroys thyroid cells.
Takes ~6 months after radioactive iodine until remission → leads to hypothyroidism
What is subclinical hyperthyroidism?
Normal T3/T4 but low TSH, often mild or asymptomatic.
Why is TSH low in primary hyperthyroidism?
T3/T4 excess suppresses TSH in a negative feedback loop.
Thyroid function test findings in primary vs. secondary hyperthyroidism?
Primary = ↑ T3/T4, ↓ TSH
Secondary (pituitary adenoma) = ↑ TSH, ↑ T3/T4
What is Graves’ Disease? What antibodies are involved?
Autoimmune disease → TSH receptor antibodies stimulate TSH receptors on thyroid → hyperthyroidism.
Antibodies: TSH Antibodies, Thyrotropin receptor antibody (TRAb) and anti thyroid peroxide antibodies (TPOAb)
Signs of Graves’ Disease?
Exophthalmos (bulging eyes)
Pretibial myxoedema (waxy oedema of the legs)
Thyroid acropachy
Diffuse goitre (without nodules)
Why should Graves’ patients stop smoking?
Smoking worsens eye complications in Graves’ Disease.
Serious side effect of Carbimazole?
Agranulocytosis
What is a thyroid storm? 3 main symptoms of it?
Life-threatening hyperthyroid crisis with:
Fever
Tachycardia
Delirium
What is thyroiditis?
Inflammation of the thyroid → initial hyperthyroidism before resolving.
4 types of thyroiditis?
(Mnemonic: Dang, Hoes Pop Dick)
De Quervain’s thyroiditis
Hashimoto’s thyroiditis (acutely hyperthyroidism, later hypothyroidism)
Postpartum thyroiditis
Drug-induced thyroiditis
What conditions is hashimotos thyroiditis associated with?
Autoimmune conditions
DIabetes
Which autoantibodies involved in Hashimotos thyroiditis
Antithyroid peroxidase and anti-thyroid globulin autoantibodies
causes of hypothyroidism?
- Hashimoto’s thyroiditis in developed world
- Iodine deficiency in developing world
- Hyperthyroidism treatment
- Lithium
- Amiodarone
- Hypopituitarism (pituitary gland doesn’t produce enough TSH
Investigations for hypothyroidism
TFTs
Thyroid Peroxidase ANtibody (TPO) screen
What would you find on a TFT for primary hypothyroidism
Low T3/T4, so high TSH
What would you find on a TFT for secondary hypothyroidism
Low TSH, low T3/T4
Management of hypothyroidism
Levothyroxine (synthetic T4)
Cause of secondary hypothyroidism
Removal of pituitary adenoma
What is subclinical hypothyroidism
Patient is asymptomatic, but has midly high TSH and normal T3/T4
