Week 6 - Thyroid Disease

Question 1

HypOthyroidism

Answer 1

Low levels of thyroid hormones
Caused by:
- autoimmune thyriditis (hashimotos disease)
- latrogenic (exposure to excessive radiation or surgical removal of part/all of thyroid

Question 2

Hashimotos disease

Answer 2

Develop antibodies against the thyroid gland, leading to its destruction and therefore low levels of T3 and Tr
Causes:
- genetic
- occur secondary to environmental radiation

Question 3

Iodine deficiency

Answer 3

Iodine is a trans element
Many poor areas of the world have dietary deficiency
If the diet is lacking in iodine for too long, the thyroid has difficulty making thyroid hormones

Question 4

Hyperthyroidism pathology

Answer 4

Excess of thyroid hormones
- Graves’ disease
- TSH-secreting pituitary tumour
- multinodular goiter
- thyroiditis
- drug indicated
- toxic adenoma
- ectopic thyroid tissue

Question 5

Presenting symptoms hypothyroidism

Answer 5

Dry,course hair
Loss of eyebrow
Puffy face
Enlarged thyroid
Slow heartbeat
Weight gain

Question 6

Presenting symptoms - hyperthyroidism

Answer 6

Hair loss
Bulging eyes
Enlarged thyroid
Sweating
Rapid heartbeat

Question 7

Hypothyroidism- treatment

Answer 7

Pharmacological therapy is based on replacing the thyroid hormones in order to restore normal concentrations

• L-thyroxine is preferred: much more shelf-stable than T3, creates a “pool” of T4 in the body that can be converted to the more active T3 when required
• T3 is much less shelf-stable than T4
• for hypothyroidism from iodine deficiency: supplement dietary iodine, restore T4/T5 levels with levothyroxime
• long standing goitres are unlikely to shrink due to treatment, the goal is to stop the growth

Question 8

Drugs - liothyronine (T3): contraindications/cautions

Answer 8

• elderly: require slower dosage adjustment and higher risk of CV ADRs
• children: not preferred in children as developing brain prefers thyroxine
• safe to use in pregnancy but rarely needed thyroxine preferred
• caution in diabetes: may need to reduce diabetic medication when starting

Question 9

Thyroxine (T4)

Answer 9

• elderly: require slower dosage adjustments and higher risk of CV ADRs
• children: preferred over T3
• safe to use, preferred
• caution in diabetes, may need to reduce diabetic medication when starting

Question 10

Hyperthyroidism- diagnosis

Answer 10

Hyperthyroidism - low free TSH and high T4 levels
Subclinical hyperthyroidism - low free TSH and normal T4 levels
- hyperthyroidism secondary to pituitary tumour - high free TSH and normal T4 levels
Hyperthyroidism secondary to pituitary tumour
- high free TSH and high T4 levels

Question 11

Hyperthyroidism- treatment

Answer 11

3 main options:
1. Pharmacotherapy
- carbimazole
- proplthiouracil
- beta blockers to control symptoms
2. Surgery
3. Radioactive iodine

Question 12

Propylthiauracil (PTU) - contraindications/cautions

Answer 12

Hyperthyroidism
- children: avoid due to higher risk of hepatotoxicity
- pregnant
- watch for fever, mouth, ulcer, sore throat, rash, abdominal pain, jaundice
- hepatic

Question 13

Carbimazole - contraindications/cautions

Answer 13

• children: not recommended due to increased risk hepatotoxicty
• watch for fever, mouth ulcer, sore throat, abdomen pain, jaundice
• monitor hepatic function regularly

Question 14

Radioactive iodine

Answer 14

Hyperthyroidism treatment
- short term: incorporated into thyroid hormones and thyroglobulin but the radioactive isotopes mean they are biologically INACTIVE
- long term: follicles with RAI and those surrounding it start to suffer necrosis
- damaged tissue can no longer produce/secrete thyroid hormones