Thyroid Disease

Question 1

What are the different test results for primary hypothyroidism vs secondary hypothyroidism?

Answer 1

Primary - High TSH and low T4.
Secondary - Low TSH and low TH

Question 2

What are the causes of hyperthyroidism?

Answer 2

• Autoimmune (Grave’s disease)
• Hot nodule
• Multinodular,
• Thyroiditis (viral, drug induced or gestational)
• Drugs induced include amiodarone or lithium

Question 3

What are the causes of hypothyroidism?

Answer 3

• Autoimmune (Hashiomotos)
• Post surgery or radioactive iodine ablation
• Drug induced
• Hypopituitarism

Question 4

Explain the formation of thyroxine

Answer 4

Iodide is absorbed by thyroid follicle cells where it is then oxidized to form iodine. The iodine is then used to form thyroxine. This is then exocytosed by TSH.
In the periphery, thyroxine is converted into the active form triiodothyronine (T3)

Question 5

What are the functions of the thyroid hormones?

Answer 5

• Increased metabolism,
• Increased growth and development,
• Increased catecholamine effect.
• This results in increased cardiac output, heart rate, stroke volume and systolic BP.
• Stimulates bone turnover,
• Stimulates gut motility,
• Increases glucose usage
• T3 acts on nuclear receptors

Question 6

What is measured in a thyroid function test?

Answer 6

• TSH and free/total thyroxine.
• Sometimes do triiodothyronine

Question 7

What is the treatment for hypothyroidism?

Answer 7

Levothyroxine 1.6mcg/Kg/Day

Question 8

Explain the presentation and causes of neonatal hypothyroidism?

Answer 8

Presentation - Coarse facial features, macroglossia, umbilical hernia, mottled, dry skin, pallor, myxoedema and goiter.
- May be caused by thyroid dysgenesis or dyshormonogenesis (affects how thyroxine is made)

Question 9

What are the investigations for thyroid disease?

Answer 9

• Thyroid function test,
• TSH receptor antibodies (graves) and thyroid peroxisomal antibody (Hashimotos)
• If antibodies are negative then do an uptake scan

Question 10

What are the signs/symptoms of hyperthyroidism

Answer 10

• Tremor, sweating, thyroid acropachy, pretibial myxoedema
• Goiter, thyroid bruit,
• Lid retraction and lid lag which are due to increased SNS activity, exophthalmos (graves), Periorbital oedema (graves) ophthalmoplegia (graves),
• AF,
• Diarrhoea,
• Muscle wasting, proximal muscle weakness

Question 11

What are the signs/symptoms of hypothyroidism?

Answer 11

• Dry, thick skin, brittle hair
• Macroglossia, puffy face, loss of lateral 1/3rd eyebrow
• Bradycardia, cardiomegaly,
• Carpal tunnel, slow relaxing reflexes, cerebellar ataxia, peripheral neuropathy

Question 12

What is the treatment for hyperthyroidism?

Answer 12

1. Beta blockers for symptomatic control,
2. Carbimazole (40mg daily) or propylthiouracil - used in pregnancy (inhibit iodine organification)
3. Radioactive iodine

Question 13

Explain the treatment for Graves eye disease

Answer 13

• Urgent ophthamology referral if poor/blurred vision or rapid change in vision.
• Give eye drops for grittiness,
• Tape eyelids shut in exophthalmos to avoid corneal damage

Question 14

What are the Joe basedow phenomenon and the Wolff Chaikoff effects

Answer 14

Jod Basedow - Iodine induced hyperthyroidism when a person is iodine deficiency (2-12 weeks)
Wolff Chaikoff effect - Iodine induced hypothyroidism as excess iodine inhibits iodide organification

Question 15

What are the two types of amiodarone thyroid disease?

Answer 15

Type 1 - Autoimmune thyrotoxicosis, treated with carbimazole.
Type 2 - Destructive thyroiditis, treated with glucocorticoids +/- ATDs (anti-thyroid drugs)

Question 16

What are the investigations of a thyroid lump?

Answer 16

FNA biopsy. If cancer then treatment is either surgery or therapeutic radioiodine

Question 17

What is the major side effect of Carbimazole?

Answer 17

Agranulocytosis - deficiency in granulocytes increasing risk of infection