17/12/18 Flashcards
Hypothyroidism
1
Q
What is the half life of levothyroxine and liothyronine?
A
Levothyroxine - 6 days
Liothyronine - 2.5 days
2
Q
What percentage of T4 and T3 is bound to a specific plasma protein?
A
Thyroid binding globulin
T4 - 99.97%
T3 - 99.7%
3
Q
What causes PBGs to increase?
A
Pregnancy
Prolonged treatment of oestrogen and phenothiazines
4
Q
What causes TBG levels to fall?
A
Malnutrition
Liver disease
5
Q
What competes for protein binding sites of TBG?
A
Phenytoin and salicylates - co-administered drugs
6
Q
Define primary hypothyroidism
A
myxoedema - autoimmune damage to the thyroid gland resulting in declining levels of thyroxine but increasing levels of TSH
7
Q
What are the symptoms of primary hypothyroidism?
A
Deepening of the voice Depression and tiredness Cold intolerance Weight gain with reduced appetite Constipation Bradycardia Eventual myxoedema coma
