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25 Cards in this Set

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Name 2 drugs which can inhibit thyroid hormone synthesis or release
Lithium & iodine (W-C block)
What impact does amiodarone have on thyroid function (3)?
1. Inhibits the enzymatic conversion of T4 -> T3
2. blocks T3 binding at nuclear receptor --> hypothyroidism
3. Direct toxic effects on thyroid follicular cells (may cause transient hyperthyroidism)
If a person with an underlying thyroid disease experiences Wolff Chakoff block, what can happen?
Failure to escape from block --> HYPOthyroidism or HYPERthyroidism
Natural hypothyroid treatment

Complications
Dessicated thyroid = T3 + T4 hog/cow/sheep

Antigenic potential, unstable and unpredictable
Synthetic hypothyroid treatment
Levothyroxine (T4) preferred over T3 or T3/T4 mixtures
Benefits of levothyroxine

What patient will start on a high dose or levothyroxine? A small dose? How is the dose adjusted?
Long T1/2, stable, not antigenic, inexpensive

High dose (50 mcg/dl) for young people or people >45 with no cardiac probs
Low dose (12.5 mcg/dl) for elderly or pts with hx of cardiac probs

Titrate based on cardiac sx and TFTs
Steady after 6-8 weeks may be able to discontinue therapy
Levothyroxine DDIs
Resin binders- cholestyramine, colestipol
Aluminum preparations- aluminum hydroxide, sucralfate
Enzyme inducers- phenytoin, rifampin, phenobarbital, carbamazepine
Increases TBG- estrogen, raloxifene (decrease free binding)
When should patient take levo? What should they avoid when they take levo?
Take it in the morning on EMPTY STOMACH.

Avoid iron containing products, calcium containing products (2 hrs before or 4-6 hours after)
True or false: there are slight dose variations from 1 brand of thyroxine compared to another.
True. For this reason, keep patient on same product if possible (monitor closely if change is necessary)
What is subclinical hypothyroidism? How is it treated?
Normal T4 with high TSH usually asymptomatic, may progress to hypothyroidism. No definitive evidence about treating these patients, may treat if TSH > 10 mIU/L
What is myxedema coma? Treatment?
End stage of untreated hypothyroidism.

Treat with IV bolus thyroxine (high dose) 300-500 micrograms + IV hydrocortisone + supportive therapy
Hyperthyroidism, DOC? Other options?
Thionamides/thioureas are DOC for kids, adolescents, graves, pregnancy
Also radioactive iodine, surgery, adjunct therapy
Thiourea drugs- examples, moa
Propylthiouracil, methimazole
MOA- inhibit TPO, inhibit coupling of iodotyrosines, inhibit peripheral conversion of T4-->T3
metabolism of thionamides? duration of treatment? Adverse effects
Hepatic

1-2 years

Benign Transient leukopenia (MOST COMMON), Agranulocytosis, Maculopapular rash, GI intolerance, arthralgias
In a patient with thionamide induced BTL what should be done?
continue therapy and monitor
Radioiodide- DOC for?? Contraindications?
Toxic autonomous nodules, multinodular goiters, elderly, cardiac disease

Breastfeeding/pregnant (goes to fetal thyroid --> thyroid destruction), children
I-131- MOA? Adverse effects?
Disrupts hormone synthesis --> necrosis and follicular breakdown --> transient increase in thyroid hormone levels

Hyper-->hypothyroid, tenderness, dysphagia
Pretreatment & Post treatment for RAI?
Pre- beta blockers (inhibit thyroid effects on HR), thionamides (in pts with long standing hyperthyroidism- quiet the gland before destruction)

Post- thionamide, BB?, iodide?

Post
When is surgery indicated for hyperthyroidism?
Malignancy, large thyroid gland, severe opthalmopathy, pressure sx/obstruction, not responding to thionamides
Pre surgical treatment
Thionamides (till pt is euthyroid), iodide, propranolol
Post surgery treatment
Propranolol (maybe iodide as well)
Potassium iodide- MOA, Use?
MOA- blocks thyroid hormone and inhibits thyroid hormone synthesis and decreases size & vascularity of the gland

Used as an adjunct (prep for surg), also used for people with exposure to a nuclear event with RADIOACTIVE IODINE CONTAMINATION
Adrenergic antagonists- use?
for thyroiditis, prep for surgery or thyroid storm (beta blockers)

If beta blockers can't be used, centrally acting sympatholytic (clonidine) or calcium channel (verapamil) can be used
Number one cause of subclinical hyperthyroidism?
Levothyroxine therapy

Low TSH, normal FT4
Thyroid storm- sx, mortality, treatment
Fever, tachycardia, tachypnea, NVD, dehydration, coma

Precipitated by infection, trauma, drug withdrawl

Mortality = 100% if not treated

Treat- Thionamides, iodides, propranolol, dialysis/plasmapheresis to remove circulating hormones