Thyroid Flashcards
__ and ___ are the biologically active hormones from the thyroid
T3 and T4
__ is made in the thyroid only, __ is made in the thyroid and outside the thyroid
T4, T3
What is the process of releasing T4 and T3
Hypothalamus-> TRH-> Anterior pituitary-> TSH->thyroid gland-> T4 and T3-> back to hypothalamus
parafollicular C cells make
calcitonin
follicle cells in thyroid make 90% __ and 10% __
T4, T3
The best and cheapest screening test for thyroid diseases is
TSH
Measure _____ to test for Hashimoto’s
TPO antibodies
Order ____ when you want to follow thyroid cancer
thyroglobulin
Measure ____ and ___ to see if Grave’s disease
TRAB and TSI
Exogenous causes of thyrotoxicosis
too much TH replacement therapy, or a TH suppressive therapy
Endogenous causes of thryotoxicoisis
Grace’s disease, thyroiditis, toxic nodular goiter
Symptoms are hyperthryoidism
intolerance to heat, fine hair, bulging eyes, facial flushing, tachycardia, increased BP, breast enlargement, weight loss, muscle wasting, menstrual changes
Gold standard for hyperthyroid is ____
nuclear medicine uptake and scan. Iodine tracer given and that helps with diagnosis (TRAB and TSI can be ordered)
Once you see that there is hyperthyroidism present, first thing to do is ____
β blocker! This is to prevent afib
What is the pathophys of Grave’s disease
Autoantibodies on thyroid hormone receptor on thyroid gland-> over production of TH
Labs for Graves disease
TSH low, T4 and T3 elevated. TRAb and TSI elevated
When should you not just order TSH and need to also order T3 and T4
first tri of pregnancy, pituitary disease, TSh still equilibrating, nonthryoidal illness, acute psychiatric illness, TSH secreting pituitary tumor, thyroid hormone resistance
Antithyroidal Medications are:
Thioamides (methimazole and propthiouracil)
MOA of thionamides
inhibit synthesis of thyroid hormones by blocking oxidation of I in thyroid gland-> block T3 production. Does not affect circulating T4 and T3
What are AEs with thionamides
rash, pruritus, GI
rare: granular cytosine (CBC if fever/sore throat), hepatotoxicity, pancreatitis, vasculitis
What medications should be given for someone who has Graves and is pregnant
PTU first tri, switch to MMI second tri. Monitor TSH and T4, keep TSH normal and T4 1.5x mroe
Thyroid storm criteria
High temp, cardiovascular events (tachycardia, afib, CHF), GI-hepatic dysfunction, CNS disturbance, history
What are the most common causes of thyroid storm
Grave’s disease, toxic adenoma and MNG, hyper functioning carcinoma, TSH secreting pituitary adenoma, strums ovary, hcg secreting tumor, IFN α and IL2
What 5 drugs should be given for thyroid storm management
antithyroidals (PTU, MMI), Iodine, β blocker, supportive (Tylenol, hydrocortisone), alternative (lithium, cholestyramine)
must block new synthesis first before giving iodine
Iodine therapy blocks the release of _____ and decreases _______
pre-stored hormone
decreases iodide transport and oxidation in follicular cells
Avoid ____ as they can increase free thyroid hormone by decreasing thyroid protein binding
salicylates
For thyroid storm, surgery would be _____. To go, hold the ___ and stop _____
Total thyroidectomy
hold the iodine, stop antithyroidals and wean β blockers
What is the role of steroids in a thyroid storm
block T4 to T3.
potential for adrenal insufficiency with autoimmune hyperthyroidism
relative adrenal insufficiency (TH-> ups cortisol metabolism-> adrenal reserve. can have longer survival with glucocorticoids)
What is Thyroiditis
inflammation of thyroid gland leading to leaking of thyroid hormone
Treatment for thyroiditis
β blockers, time, sometimes steroids
What are the two types of amiodorone induced thryroiditis and how to treat
type 1: large iodine load-> excessive TH. treat with antithyroidals
Type 2: iodine or drug destroys gland, treat with steroids
What are the labs with hypothyroidism
High TSH and low free T4
Does ultrasound tell you anything when trying to determine thyroid size
no, get nuclear imaging
What level of TSH do you need to treat for hypothyroidism
TSH>10 always (if elevated but T4 normal, can still treat)
What are the most common treatment options for hypothyroidism
synthetic T4 or levothyroxine
T4/T3 combos from bovine or porcine
Most common cause of hypothyroidism in countries with access to iodine is _____ or _____
Hashimoto’s or autoimmune thyroid disease
What are the two categories of dosing for replacement thyroid hormone (high dose vs low dose)
high dose: hx of thyroid removal or PROFOUNDLY elevated TSH
Low: hypothyroidism not profound but elevated
When to take thyroid hormone
First thing in the morning, 4 hours before vitamins and an hour before meals
What is the big risk for hypothyroidism
Myxedema coma
What are some myxedema coma precipitating factors
Drugs, Infections, CNS events, CHF, hypothermic insult, trauma, metabolic disurbance, GI bleeding, raw bok choy
Treatments for myxedema coma
T4, T3, or Combination
continued ECG monitoring
Besides medication, what other treatment needs to be given for a myxedema coma
ventilatory support, warming, manage bradycardia and hypotension, hyponatremia, glucocorticoid therapy
What are malignancy risk for thyroid cancers (Nodule)
Hx, PET avid nodule, ionizing or craniocervical radiation, hyper Ca2+, FH of MEN2
What are the types of thyroid cancer
papillary, follicular, medullary, anaplastic
worst prog is anapestic
