L7 Thyroid Hormone Physiology Flashcards
Describe the microscopic features of the thyroid gland
follicles consisting of monolayer of epithelial cells
enclosing a large core of viscous, homogenenous colloid
colloid acts as a reservoir of thyroid hormone
What are the primary hormones secreted by the thyroid gland? [3]
T3
T4
Calcitonin
Calcitonin
concerned with calcium homeostasis
Carbimazole
- MOA
- Name of active form
Anti-thyroid drugs
Active form is -methimazole
inhibit synthesis of thyroid hormones by preventing the incorporation of the iodide into the thyroglobulin which is a precusor for thyroid hormones
Prophylthiouracil
Drug that prevents the peripheral conversion of T4 to T3.
Used to treat hyperthyroidism
Drug of choice to treat hyperthyroidism in first trimester.
What can iodine deficiency lead to?
Raised levels of TSH
Leading to enlarged thyroid (GOITRE)
List the effects of thyroid hormones
-increase basal metabolic rate rate: -increased in carbohydrate metabolism -increased in the synthesis, mobilisation and degradation of lipids -increased protein synthesis.
Levothyroxine
- used to treat thyroid deficiency (hypothyroidism)
- can suppress TSH secretion (tumours)
- IV/oral
good oral bioavailability
high protein binding
Potassium perchlorate
acts by competing with iodide for the active iodide uptake pump.
Why can radioactive iodine be used to treat thyroid deficiency?
Can be selectively concentrated in the thyroid gland where it causes tissue damage and therefore reduced thyroid hormone secretion.
Drugs which can induce goitre
lithium which is used in the treatment of bipolar depression,
iodides which are contained in vitamin preparations and some cough remedies.
How is T4 transported around the body?
transported in the blood via thyronine-binding globulin (TBG)
