1(E): Hypothyroidism Flashcards
What is myxoedema
Clinical manifestation of thyroid hormone deficiency
What is the stereotype for hypothyroidism
Women over-40
What is primary hypothyroidism
Defect in thyroid gland: low T3, T4
What is secondary hypothyroidism
Defect in pituitary gland: low TSH
What is tertiary hypothyroidism
Defect in hypothalamus: low TRH
What are the two aetiological categories of hypothyroidism
Autoimmune
Acquired
What are two autoimmune conditions causing hypothyroidism
- Hashimoto’s
- Primary atrophic hypothyroidism
What is primary atrophic hypothyroidism
Diffuse lymphocytic infiltration of the thyroid gland causing atrophy
What is a feature of primary atrophic hypothyroidism
No goitre
What is the most common cause of hypothyroidism in wester civilisation
Hashimoto’s disease
when is Hashimoto’s more common
Women over-60
what is the most common cause of Hashimoto’s in developing countries
iodine deficiency
what are 4 acquired causes of hypothyroidism
- post thyroidectomy
- radio-iodine treatment
- drug induced
- de quervains subacute thyroiditis
- post-partum thyroiditis
what medications can cause hypothyroidism
amiodarone
carbimazole
lithium
explain hypothyroidism in de quervains thyroiditis
after period hyperthyroidism, can lead to hypothyroidism
explain postpartum thyroiditis
after pregnancy can have period of hypothyroidism
what can cause secondary hypothyroidism
pituitary adenoma
what are signs of hypothyroidism
Bradycardia Reflexes diminished Ataxia Defeated demeanour Yawning Cold hands Ascites and non-pitting oedema, pericardial effusion Round puff face Dry hair and skin Immobile/ileus CCF
when does sick euthyroid syndrome occur
In patients who are critically unwell or severe stress
when does sick euthyroid syndrome occur more
ITU patients
explain thyroid function in sick euthyroid
Normal thyroid function - no symptoms of hyper or hypothyroidism, however, cytokines alter circulating thyroid hormone
What is first line investigation for hypothyroidism disease
TFTs
How do TFTs present in primary hypothyroidism
- Low T3, T4
- High TSH
How do TFTs present in secondary hypothyroidism
- Low T3, T4
- Low TSH
How do TFTs present in sick euthyroid syndrome
- Low TSH
- Low T3, T4
How do TFTs present in subclinical hypothyroidism
- High TSH
- Normal T3, T4
How do TFTs present if poor compliance with thyroxine
- High TSH
- Normal T3, T4
Why is lipid profile ordered in hypothyroidism
Untreated hypothyroidism can increase VLDL and Ldl
What autoantibodies are present in hypothyroidism
- anti-TPO (thyroid peroxidase)
What is given to manage hypothyroidism
Thyroxine
How long is waited after giving thyroxine to measure TFTs
4 Weeks
What is risk with thyroxine
Can precipitate angina, MI
What are 3 risks of hypothyroidism
- Carpal tunnel
- Myxoedema coma
- CVD
What are 4 risks of hypothyroidism in pregnancy
- Pre-eclampsia
- Anaemia
- Pre mature
- PPH
What is myoexdema coma
Acute exacerbation of hypothyroidism
What age does myxoedema coma occur
Over 65 year-olds
What are 5 causes of myxoedema coma
- MI
- Infection
- Trauma
- Stroke
- Post thyroidectomy
Explain how myxoedema coma presents
Altered mental status
Seizures
Bradycardia
Hyporeflexia
Hypothermia
Hypoglycaemia
Where should myoexdema patients be managed
ICU
What is given in myoexedma coma
If suspect pituitary disorder give hydrocortisone first. Then Liothyronine (T3) [If do not suspect pituitary - just give liothyronine]
