Thyroid_Hypothyroidism

Question 1

Causes:

Answer 1

Autoimmune: Hashimoto’s
Iodine Deficiency or Iodine Induced
Transient Thyroiditis (subacute, silent, postpartum, early postablative therapy)
Iatrogenic (thyroidectomy, radioiodine therapy)
Drug induced:

(RACGP article hypothyroidism Ix and Mx)

Question 2

What are the drug induced causes of hypothyroidism?

Answer 2

Carbimazole
Propylthiouracial
Iodine 
Amiodarone
Lithium 
Inteferons 
Thalidomide
Sunitinib
Rifampicin 
(RACGP article hypothyroidism Ix and Mx)

Question 3

Dose aim for thyroxine replacement?

Answer 3

1.6micrograms/kg of bodyweight

Question 4

What is the follow up of patient with TSH 4-10 with nil symptoms with:

a) TPO Antibody +ve
b) TPO Antibody -ve

Answer 4

nil treatment required as not symptomatic

a) follow up in 3/12 then every 6-12/12
b) 12 monthly f/up.

If TSH persistently >10 then may require starting treatment or if associated with dyslipidaemia.

(Ref: ETG)

Question 5

1. Cause of high TSH+ low T4

2. Normal TSH + low T4

Answer 5

1. Primary Hypothyroidism
2. Secondary hypothyroidism (pituitary or hypothalamus) OR severe nonthyroidal illness
   (RACGP article hypothyroidism Ix and Mx)

Question 6

Medications which increase thyroxine requirement:

Answer 6

OCP
anti-epileptic medication (eg. carbamazepine, phenytoin)
some antibiotics (eg. rifampicin)
the new tyrosine kinase inhibitors (eg. imatinib).
(RACGP article hypothyroidism Ix and Mx)

Question 7

Drugs that have been shown to reduce absorption include

Answer 7

• calcium carbonate
• ferrous sulphate
• multivitamins
• cholestyramine
• phosphate binders
• proton pump inhibitors
(RACGP article hypothyroidism Ix and Mx)