Hypothyroidism Flashcards
What is hypothyroidism?
Clinical state due to reduced production of free T3/4, 95% of which are due to primary hypothyroidism where the thyroid gland fails to produce thyroid hormone
Epidemiology of hypothyroidism
More prevalent in the developing world
Females: Male 6:1
Increases with age >40 most common
Aetiology of hypothyroidism
Autoimmune thyroiditis (Atrophic / hashimotos) most common UK
Iodine deficiency: most common worldwide
Others: radio iodine therapy, previous surgery
Drugs: amiodarone + lithium + thalidomide
Pathophysiology of hypothyroidism
T4 is usually converted to T3 in target tissues. A failure to produce the free Ts = stimulation of PG to increase TSH secretion. This is the normal negative feedback mechanism which is impaired in hypothyroidism
Features of autoimmune thyroiditis
With a goitre = hashimotos
- may go through initial hyperthyroid episode
- anti TPO positive
Without a goitre = atrophic thyroiditis
-anti TPO + anti-TSH positive
Risk factors for hypothyroidism
Low iodine Female gender Middle age Positive family history Autoimmune disorder Graves disease Radiotherapy Previous surgery Downs and turners
Acronym to remember signs and symptoms
MOMS SO TIRED
Memory loss / Mood low Obesity Malay flush Slowness / Slow reflexes Skin dry Onset: gradual Tired Intolerance to cold / increased weight Raised BP Energy low Depressed / decrease appetite
Signs other than MOMS SO TIRED
Bradycardia
Puffy face
Goitre
Investigations to consider in hypothyroidism
Serum TSH raised Free T4 low FBC would show a normoocytic anaemia Serum cholesterol increased Antibodies positive
Management in hypothyroidism
Levothyroxine
Features of myxoedema coma
Severe hypothyroidism Hypothermia Hypoglycemia Heart failure (brady + hypotension) Coma
