Hypothyroidism Flashcards
what is hypothyroidism
insufficiency in the level of thyroid hormones circulating
what is the difference between primary and secondary hypothyroidism
primary- damage to the thyroid gland itself causes deficiency in thyroid hormone
secondary- underproduction of TSH by the pituitary gland causes less thyroid hormone to be released by the thyroid gland
what are the two thyroid hormones
T4- thyroxine
T3- triiodothyronine
T4 half life?
5-7 days
T3 half life?
24 hours
aetiology/ causes of PRIMARY hypothyroidism?
acquired hypothyroidism;
Hashimotos Thyroiditis (autoimmune)
severe iodine deficiency
iodine excess
iatrogenic (post-surgery, radioactive iodine)
Congenital diseases;
inherited defects of the thyroid
causes of secondary hypothyroidism
Pituitary and Hypothalamic Disease - resulting in reduced TSH and TRH and, hence, reduced stimulation of thyroid hormone production
in what areas of the world is iodine deficiency more common
Himalayas
risk factors for hypothyroidism
History of surgery or radioiodine therapy for hyperthyroidism
Personal/family history of other autoimmune conditions (e.g. Addison’s, type 1 diabetes mellitus)
presenting symptoms and signs of hypothyroidism
INSIDIOUS onset
Cold intolerance
Lethargy
Weight gain
Reduced appetite
Constipation
Dry skin
Hair loss
Hoarse voice
Mental slowness
Depression
Cramps
Ataxia
Paraesthesia
Menstrual disturbance (irregular cycles, menorrhagia)
what is myxoedema coma
severe hypothyroid usually seen in the elderly
Hypothermia Hypoventilation Hyponatraemia Heart failure Confusion Coma
signs of hypothyroidism on physical examination
Hands
Bradycardia
Cold hands
Head/Neck/Skin Pale puffy face Goitre Oedema Hair loss Dry skin Vitiligo
Chest
Pericardial effusion
Pleural effusion
Abdomen
Ascites
Neurological
Slow relaxation of reflexes
Signs of carpal tunnel syndrome
investigations for hypothyroidism
bloods; FBC, CRP, ESR, Thyroid function tests (TSH, T3, T4) and cholesterol
how to treat hypothyroidism
levothyroxine
main issue with levothyroxine in treating hypothyroidism
can cause hyperthyroid
