Thyroid Disease - Hypothyroidism

Question 1

Aetiology of Hypothyroidism (5).

Answer 1

1. Hashimoto’s Thyroiditis (commonest in developed world).
2. Iodine Deficiency (commonest in developing world).
3. Management of Hyperthyroidism.
4. Medications.
5. Central Causes that cause Secondary Hypothyroidism.

Question 2

How is an iodine deficiency prevented?

Answer 2

Additive to foods e.g. table salt.

Question 3

Drugs that can cause Hypothyroidism (2).

Answer 3

1. Lithium - Inhibits Production of Thyroid Hormones = Goitre + Hypothyroidism.
2. Amiodarone - Interferes with Production of Thyroid Hormones and Metabolism = Hypothyroidism + Thyrotoxicosis.

Question 4

Causes of Secondary Hypothyroidism (4).

Answer 4

Hypopituitarism (Failure to Produce Enough TSH) -
1. Tumours.
2. Infection.
3. Vascular e.g. Sheehan Syndrome.
4. Radiation.

Question 5

What is Hashimoto’s thyroiditis?

Answer 5

Autoimmune inflammation of the thyroid gland by anti-TPO and anti-TBG antibodies.

Question 6

Effect of Hashimoto’s Thyroiditis on Thyroid Gland 2).

Answer 6

1. Initially - Firm and Non-Tender Goitre (Transient Thyrotoxicosis in Acute Phase).
2. Atrophy of the Thyroid Gland.

Question 7

Associations of Hashimoto’s thyroiditis (4).

Answer 7

1. Type I Diabetes Mellitus, Coeliac Disease, Vitiligo.
2. Addison’s disease.
3. Pernicious Anaemia.
4. MALT Lymphoma.

Question 8

What is Riedel’s Thyroiditis?

Answer 8

Dense fibrous tissue replaces the normal thyroid parenchyma - hard, fixed, painless goitre with retroperitoneal fibrosis = hypothyroidism.

Question 9

Clinical Features of Hypothyroidism (8).

Answer 9

1. Weight Gain.
2. Fatigue.
3. Dry Skin (Anhidrosis), Cold and Yellowish Skin.
4. Coarse Skin and Hair Loss (Lateral Eyebrows and Scalp).
5. Fluid Retention (Oedema, Effusions, Ascites).
6. Heavy/Irregular Periods.
7. Constipation.
8. Decreased Deep Tendon Reflexes and Carpal Tunnel Syndrome.

Question 10

Management of Hypothyroidism (4).

Answer 10

1. Replacement - Oral Levothyroxine (Synthetic T4 which can metabolise to T3) - titrate dose until TSH levels are normal.
2. Monitor TSH levels monthly until stable - check less frequently after that.
3. Use lower dose for Cardiac Disease, Severe Cases, 50+ Cases.
4. Use higher dose in Pregnancy.

Question 11

Adverse Effects of Thyroxine Therapy (4).

Answer 11

1. Hyperthyroidism.
2. Reduced Bone Mineral Density.
3. Worsening of Angina.
4. Atrial Fibrillation.

Question 12

Interactions of Thyroxine with Other Drugs.

Answer 12

Give Iron and Calcium Carbonate at least 4 hours apart (since the absorption is reduced).