Thyroid Flashcards
What is T4?
Precursor to thyroid hormone - goes into organ of function to be converted into functioning of molecule
What is T3?
Thyroid hormone (2 tyrosine linked + iodine)
What are the results of the thyroid function tests if dx = hypothyroidism?***
T4: low, T3: normal or low, TSH: high, serum thyroglobulin: low
What are the results of the thyroid function tests if dx = hyperthyroidism?***
T4: high, T3: high, TSH: low, serum thyroglobulin: high
What is Hashimoto’s Thyroiditis?
Autoimmune disorder: antibodies against thyroid peroxidase and/or thyroglobulin destroy thyroid gland follicles
Name clinical presentations of hypothyroidism:
- Slowing of body functions (bc thyroid hormones stimulate response of adrenergic system)
- Puffiness, droopy eyelids, coarse/thin hair
- Saddle nose, thickened lips
Name sx of Hashimoto’s thyroiditis (HT):
- goiter
- slower metabolism
- weight gain
- fatigue
- depression
- bradycardia
- constipation
- muscle weakness
- memory loss
- infertility
- hair loss
- reaction hyperthyroidism
What is HT often misdiagnosed as?
- depression
- anxiety
- bipolar
How is HT detected?
- Presence of specific antibodies against thyroglobulin and thyroid peroxidase
- Increased TSH
- Lymphocyte invasion of thyroid gland
- detected via radioactive uptake scan (iodine), ultrasound*
What is a precaution with thyroid hormone tx for hypothyroidism?
May increase adrenergic receptor sensitivity to catecholamines (normal levels of NE/E, but hyper response)
What is the effect of hypo/hyperthyroidism in regards to pregnancy?
Hypo: difficulty becoming pregnant
Hyper: abortion common when pregnant
What is used to tx hypothyroidism?
Iodine: if due to iodine deficiency (seen in elderly/poor)
T4: if due to gland failure (body converts T4 to T3 PRN)
What is the most common form of hyperthyroidism?
Grave’s disease
Grave’s disease pathopysiology:
Activates antibody to TSH receptor –> increased T3 and T4
Name 3 dx parameters for hyperthyroidism:
1) < 40 y/o - nervous system effects seen
2) > 40 y/o - CV effects seen
3) catacholamine response
What is the treatment of choice for hyperthyroidism:
radioiodine (131T)
Radioiodine MOA:
Ionizing radiation destroys the gland
What is a caution with radio iodine tx?
Other antithyroid drugs bc radioiodine must be concentrated into uptake gland (management: stop anti-thyroid drug 2 days before and after)
Why are other antithyroid drugs a caution in tx with radio iodine?
Other antithyroid drugs bc radioiodine must be concentrated into uptake gland (management: stop anti-thyroid drug 2 days before and after)
Radio iodine is CI in?
Pregnancy and children
What are 4 precautions in radio iodine tx?
1) delay in response (2-6 months)
2) radiation-induced thyroiditis
3) hypothyroidism
4) thyroid cancer
Thioamide drugs MOA:
blocks thyroid hormone synthesis (onset needs depletion of thyroid hormone stores)
Thioamide drug therapy schedule:
therapy is adjusted and/or reduced every 4-6 weeks
What are 2 advantages of PTU?
1) Fast decrease in T3 due to its peripheral effects
2) Preferred in pregnancy bc does not cross placenta extensively, no teratogenic reports, only 1/10 crosses into breast milk
