Hypo general
What is different between subclinical and overt hypothyroidism?
Subclinical: high TSH. normal free T4, may be asymptomatic or have mild symptoms, decision to treat is individualized
Overt: very high TSH, low free T4, usually treated
What diagnostic tool can be used for hypothyroidism?
TSH levels, should be high due to low T4
What is Liotrix?
T4 and T3
Not routinely recommended, high cost, lack of therapeutic rationale, no additional benefit over T4 monotherapy
What are the possible causes for hyperthyroidism? What medications could induce?
Grave's disease, thyroid nodules, thyroiditis, drug induced (iodine, amiodarone, interferons)
What are some s/sx of hyperthyroidism?
anxiety, weakness, increased metabolism, warm and moist skin, arrhythmias, tachycardia, protruding eyes
What medications are risk factors for hypothyroidism?
amiodarone, lithium, interferons, tyrosine kinase inhibitors, carbamazepine
What are the treatment goals for hypothyroidism?
Minimize or alleviate symptoms, achieve stable euthyroid state, avoid overtreatment, decrease risk of adverse outcomes
What is Liothyronine? When is it used? What are the disadvantages?
synthetic T3
not routinely recommended, IV can be used to treat myxedema coma
it is the active form of thyroid hormone, short half life, expensive
What is Grave's disease? What is the treatment for a pregnant pt with grave's disease and what is contraindicated?
autoimmune syndrome when immune system stimulates thyroid gland via thyrotropin receptor antibodies (TRAb) causing increase production of T4
Propylthiouracil for first trimester, methimazole for second and third
CI: RAI, surgery
What are the treatment goals for hyperthyroidism?
eliminate excess thyroid hormone, minimize symptoms and long term consequences
What is the etiology behind primary hypothyroidism? secondary? tertiary?
Primary: Hashimoto's disease (autoimmune), surgical gland removal, thyroid irradiation, drug induced
secondary: pituitary failure (decreased TSH)
tertiary: hypothalamic failure (decreased TRH)
For subclinical hypothyroidism, what starting dose of of levothyroxine should be initiated?
12.5-50 mcg daily and titrate dose every 6-8 weeks per TSH level
What is desiccated thyroid? Disadvantages?
Porcine derived T4/3 combo
Not recommended, strongly recommended against per Beers Criteria
Potency varies, ratio of T3 is higher, risk of antigenic reaction
When is a thyroidectomy indicated and what is a requirement prior to surgery? What is used pharmacotherapy wise for pretreatment and after?
planning pregnancy in less than 6 months, symptomatic goiters, low RAI uptake
Candidates must be euthyroid prior to surgery
Use methimazole +/- propranolol for pretreatment, give iodide 10 days before surgery to decrease thyroid blood flow
After surgery, initiate levothyroxine, wean beta blocker after tachycardia resolves
What are the treatment options for hyperthyroidism?
surgery, thionamide drugs, iodides, radioactive iodine
Clinical presentation of hypothyroidism?
tiredness, weakness, constipation, dry skin, cold intolerance, weight gain, hoarse voice, muscle pain, maybe goiter, dry coarse skin and cool extremities, myxedema, bradycardia, elevated cholesterol, infertility
What is the BBW for all thyroid hormone products?
weight reduction
What is the DOC for pregnancy (caution with?)? What needs to be done to the dose? How is dosing done in children?
levothyroxin, caution with prenatal vitamins
Dose needs to be increased by 30-50% as soon as pregnancy is detected
age and weight based dosing
Iodides MOA, onset, place in therapy, AEs?
blocks thyroid hormone biosynthesis and release
1-2 weeks
pre-op 7-14 days before surgery, give 3-7 days after RAI
AE: hypersensitivity, salivary gland swelling, iodism (metallic tasts, sore teeth, etc), gynecomastia
What is the treatment regimen for thyroid storm?
Propylthiouracil, iodine suppresses hormone synthesis and release, esmolol or propranolol decreases heart rate, corticosteroids act as an antipyretic and stabilize blood pressure
What is first line for hypothyroidism? How do we dose it? When and what do we follow up and monitor?
Levothyroxine
if under 50, 1.6 mcg/kg/day using IBW, if over 50 with CHD 50 mcg daily, if history of CHD 12.5-25 mcg daily, if subclinical 12.5-50 mcg daily
Check TSH 4-6 weeks and adjust dosages until euthyroid, titrate by12.5-25 mcg increments
What are the important clinical notes for levothyroxine? (diet, drug, manufactorer)
Taking with food can decrease absorption, consistency and compliance is key
Do not take with Ca, iron containing supplements, antacids, bile acid sequestrants, sevelamer, sucralfate
Keep pt on same manufacturer, very narrow therapeutic index
What is the treatment for Myxedema coma?
IV levothyroxine, add on IV liothyronine, can also add IV hydrocortisone
Radioactive iodine place in therapy, agent of choice, MOA, onset of action, AEs, monitoring?
Planning to get pregnant in greater than 6 months, increased surgical risk, failure to achieve euthyroid state, liver disease, HF
131I - MOA: beta and gamma concentrates in thyroid to permanently damage and destroy the tissue, thyroid hormone production is reduced
euthyroid after 6-8 weeks
AEs: thyroid tenderness, dysphagia, may induce hypothyroidism, pregnancy and breastfeeding (absolute CI)
Monitor within first 1-2 months, assess total T3 and TSH, once hypothyroid initiate levothyroxine
What are the 2 antithyroid drugs (thionamides) and which is preferred? MOA? AEs? Monitoring and follow up? length of therapy?
Methimazole (preferred) and propylthiouracil
Methimazole: blocks thyroid hormone production from thyroid gland by blocking oxidation of iodine and preventing synthesis of T3/4
PTU: prevents synthesis of T3/4 and blocks conversion of T4 to T3
AEs: leukopenia, GI, rashes, arthralgias, fever, hepatotoxicity, agranulocytosis
Monitor for s/sx of illness, measure serum T3 and T4 2-6 weeks after initiation, symptoms of febrile illness and liver injury
stop or taper after 12-24 months
when pt goes into remission, evaluate for recurrence every 6-12 months after, if relapse, give radioactive iodine