thyroid Flashcards
which is the active form of thyroid hormone?
T3.
what enzyme is responsible for the peripheral conversion of T4-T3
thyroperoxidase -inhibited by PTU
what does thyroid hormone do to the body>
affects also every system in the body. increases oxygen consumption, metabolism of fats, carbs and proteins, vitamin secretion, breakdown of other hormones, growth and differentiation.
what is the most common thyroid supplement?
levothyroxine. which is a synthetic t4 replacement
liothyronine
t3 replacement
liotrix.
t3/t4 mixed replacement
is there any benefit in t3 over t4 replacment/
no
levothyroxine half life
6-7 days.
levothyroxine time to peak affect
3-4 weeks
who requires more thyroid hormone per weight?
children.
who should be initiated on lower doses of levo?
patients with angina. then gradually increased..
why use liothyronine?
more rapidly effective. peaks in 2-4 hours.
what is the half life of liothyronine
1 day
when is liothyronione typically used?
only in emergencies like myxedema coma. because its more expensive has a lower half life, etc. less stable
what does lack dietary iodine cause?
endemic goiter, or idoine deficient goiter. this is hypothyroidism.
what are the common causes of hyperthyroidism
Graves, thyroid nodule, thyroiditis, thyroid cancer
lab findings for hyperthyroidism
low TSH, t3-t4 usually increased.
how can medically treat hyperthyroidism?
propylthiouracil, methimazole, carbimazole
how does the medical treatment of hyperthyroidism work?
inhibition of the organification and coupling of iodide and iodotyrosine. this is inhibition of thyroid peroxidase. there is peripheral inhibition of conversion
what route is the best for thyrotoxicosis
rectally
what are the important side effects of these drugs
lupus-like syndrome. agranulocytosis and hepatitis
what is the goal of radioactive iodine?
to destroy enough tissue as to become euthyroid
what type of rays are emitted with radioactive thyroid
beta particles and gamma rays
what are the contraindications for radioactive therapy
pregnancy and breast feeding
what are children with hyperthyroid usually treated with?
even though radioactivity is a legitimate alternative they are usually treated with medications.
what beta blocker s are used in hyperthyroidism, why?
propanolol, metoprolol, atenolol and nadolol. to control anxiety and tremor as well as palpitations
when are beta blockers indicated?
when the symptoms are severe
