Therapeutics of thyroid disease

Question 1

Principles of managing endocrine disease

Answer 1

Overactive gland:
- inhibit hormone synthesis
- inhibit hormone action 
- remove/destroy gland
Underactive gland - replace missing hormones

Question 2

Thyrotoxicosis

Answer 2

Excessive production of thyroid hormone

Question 3

Causes of thyrotoxicosis

Answer 3

• autoimmune stimulation of thyroid gland (Grave’s)
• toxic nodule disease
• chemical toxicity (amiodarone)
• destructive thyroiditis (AI or viral)

Question 4

Effects of thyrotoxicosis

Answer 4

• Increased metabolic rate –> weight loss, increased appetite, tiredness, heat intolerance, weakness, diarrhoea, anxiety
• Increased sympathetic drive –> sweating, tachycardia, tremor, lid retraction
• Goitre
• Opthalmopathy

Question 5

Management options for thyrotoxicosis

Answer 5

• inhibit thyroid hormone synthesis (thionamides)
• destroy thyroid - radioactive iodine
• remove thyroid gland (rare)

Question 6

Thionamides

Answer 6

• inhibit thyroid hormone synthesis by inhibiting thyroid peroxidase, used for thyrotoxicosis
• carbimazole or propylthiouracil
• 12-18month course - 1st line treatment for Grave’s
• full control after weeks

Question 7

Thionamides in tachycardia/tremor

Answer 7

If tachycardia/tremor present in someone with thyrotoxicosis, give beta blockers alongside thoinamides to block peripheral thyroid hormone action until thionamides work

Question 8

Problems with thionamides

Answer 8

• minor s/e: rash, pruritis, n&v, arthralgias
• agranulocytosis (sudden drop in neutrophils) - rare
• hepatotoxicity - more with PTU
• teratogenic - carbimazole
• carbimazole normaly safer except in pregnancy

Question 9

Indication and mechanism for radioactive iodine

Answer 9

Indications
-autonomous nodular disease
-relapse of Graves disease
Mechanism - destroys part of thyroid gland, reducing the capacity to generate thyroxine

Question 10

Contraindication to radioactive iodine

Answer 10

absolute - pregnancy

relative - moderate/severe thyroid eye disease (can make it worse)

Question 11

Indications for thyroid surgery

Answer 11

• florid thyrotoxicosis not responding to thionamides
• patient preference over radioactive iodine
• large goitre associated with compressive symptoms

Question 12

Problem with thyroid surgery

Answer 12

High disease recurrence rates with partial thyroidectomy

Question 13

Causes of hypothyroidism

Answer 13

• usually autoimmune
• iatrogenic (surgery/drugs/radio-iodine)
• Iodine deficiency (rare in UK)
• congenital/developmental
• pituitary disease

Question 14

Symptoms of hypothyroidism

Answer 14

• tiredness, cold intolerance, weight gain, dry skin and hair
• hoarse voice, bradycardia, puffy face, hypothermia, deafness
• growth arrest in children

Question 15

Treatment of hypothyroidism

Answer 15

Levothyroxine 50-150mcg/day

• inactive hormone - thyroxine (T4) is converted to T3 in peripheral tissues
• aim for normal TSH
• no adverse effects unless over-treated