Hypo/hyperthyroidism Flashcards
What are the causes of hypo and hyperthyroidism?
Autoimmune- Hashimoto’s thyroiditis or Grave’s disease
What hormones are involved in the release of T3 and T4 and how does the feedback loop work?
Thyrotropin releasing hormone from the hypothalamus stimulates thyroid stimulating hormone from the pituitary gland. Production of T3 and T4 negatively feedbacks on TRH and TSH
What are the causes of hypothyroidism?
Congenital- thyroid agenesis, iodine deficiency
Acquired- pituitary adenoma (secondary), iatrogenic, drug induced, Hashimoto’s thyroiditis,
What drugs can cause hypothyroidism?
Anti-thyroid drugs
Amiodarone
Lithium
Immune checkpoint inhibitors
What antibodies should be checked in hypothyroidism?
Anti-thyroid Peroxidase Antibodies (TPO)
What antibodies should be checked in hypothyroidism?
Thyroid Peroxidase Antibodies (TPO)
What is the management of hypothyroidism?
Levothyroxine
Typically start on 100mcg then recheck TFTs in 4-6 weeks and adjust on results/symptoms
Take same time each day on empty stomach, before any other medicines
Lower doses if elderly or IHD (start on 50mcg)
What is the management of subclinical hypothyroidism?
A TSH between 4.78-10.0 should be assessed but not automatically treated
Treat if pregnant, or if infertility present, symptomatic, high CV risk, goitre, positive anti-TPO antibodies
If not treating recheck after 3-6 months, then 6-12 monthly
Anti-TPO antibodies predict the risk of overt hypothyroidism
Treatment is recommended if TSH>10 mIU/L due to high risk of progression to overt hypothyroidism
What are the causes of hyperthyroidism?
Grave's Disease Iatrogenic Multinodular Goitre Toxic adenoma Thyroiditis (postpartum, subacute)
What eye signs can be seen in hyperthyroidism?
Lid lag Lid retraction Periorbital oedema Proptosis/exophthalmos Redness Ophthalmoplegia causing diplopia Ask about redness or grittiness of the eyes
What eye signs can be seen in hyperthyroidism?
Lid lag Lid retraction Periorbital oedema Proptosis Redness Ophthalmoplegia causing diplopia Ask about redness or grittiness of the eyes
What antibodies can be checked in hyperthyroidism?
TSH Receptor Antibodies
TPO Antibodies
What scan can be used to differentiate between the causes of hyperthyroidism? What would the scan look like in each cause?
Radioisotope uptake scan of thyroid
Grave’s-diffuse uptake
Nodules-uptake where the nodules are
Thyroiditis- low/no uptake
What is the management of hyperthyrodism?
Depends on the cause
Treat thyroiditis symptomatically (propranolol)
Surgery for nodules that have compression symptoms or the drugs haven’t worked
Radioactive iodine if the drugs haven’t worked, ideal therapy for multinodular (not ideal if young kids in house)
What drugs are used in hyperthyroidism and what are their side effects?
Carbimazole- First line, usually given for 12-18 months, agranulocytosis
Propylthiouracil- given if carbimazole intolerant or first trimester, agranulocytosis, deranged LFT’s
