Hypothyroidism Flashcards
define hypothyroidism?
the clinical syndrome resulting from insufficiency secretion of thyroid hormones
categorised into
- primary hypothyroidism
- secondary hypothyroidism,
define primary hypothyroidism?
o decreased thyroid hormone production from the thyroid
define secondary hypothyroidism?
o Pituitary and Hypothalamic Disease - resulting in reduced TSH, hence, reduced stimulation of thyroid hormone production
what are the causes of primary hypothyroidism?
• Hashimoto's thyroiditis • Iatrogenic • Severe dietary iodine deficiency • Iodine excess • Subacute Thyroiditis (De Quervains) o Congenital
features of hashimotos?
o Autoimmune cause
o Thyrotoxicosis in the acute phase
o More common in women
o Associated with T1DM, addisons, pernicious anaemia
features of iatrogenic hypothyroidism?
o Post-surgery
o Radioiodine
o Carbimazole
o Lithium
features of severe lithium iodine deficiency?
o Common in the developing world
o Common in mountainous areas
features of iodine excess?
o Wolff-Chaikoff effect
o Associated with taking amiodarone
features of subacute thyroiditis?
o Post viral infection
o Presents initially with hyperthyroidism
what causes secondary hypothyroidism?
o Pituitary and Hypothalamic Disease
epidemiology of hypothyroidism?
- more common in females
- age of onset >40
presenting symptoms of hypothyroidism?
Weight gain Lethargy Cold intolerance Dry (anhydrosis), cold, yellowish skin Non-pitting oedema (e.g. hands, face) Dry, coarse scalp hair, loss of lateral aspect of eyebrows Constipation Menorrhagia Decreased deep tendon reflexes Carpal tunnel syndrome
features of a myxoedema coma?
o Hypothermia o Hypoventilation o Hyponatraemia o Heart failure o Hyporeflexia o Bradycardia o Seizures o Confusion o Coma
signs of hypothyroidism in the hands?
o Bradycardia
o Cold hands
signs of hypothyroidism in Head/Neck/Skin?
o Pale puffy face o Goitre o Oedema o Hair loss o Dry skin o Vitiligo
signs of hypothyroidism in chest?
o Pericardial effusion
o Pleural effusion
signs of hypothyroidism in the abdomen?
o Ascites
signs of hypothyroidism neurologically?
o Slow relaxation of reflexes
o Signs of carpal tunnel syndrome
what blood results might you get?
o TFTs – TSH, T4, T3
Primary hypothyroidism = high TSH, low T4
Secondary hypothyroidism = low TSH, low T4
o FBC - may show normocytic anaemia
o U&Es - may show low sodium
o Cholesterol - may be high
o Autoantibodies
which bloods are most important?
TSH
what antibodies should be monitored?
- Anti-thyroid peroxidase (hashimotos)
- TSH receptor antibodies (graves)
- Thyroglobulin antibodies
how is hypothyroidism treated?
o Levothyroxine
how to manage MYXOEDEMA COMA ?
o Oxygen o Rewarming o Rehydration o IV T4/T3 o IV hydrocortisone o Treat underlying cause
complications of hypothyroidism?
- Myxoedema coma
- Myxoedema madness
- Over-replacement with thyroxine increases risk of osteoporosis
prognosis?
- Lifelong levothyroxine is required
* Myxoedema coma mortality = 80%
