Thyroid Flashcards
Medications that can affect TSH secretion
Decrease TSH
-dopamine, high dose glucocorticoids, octreotide (GOD)
Increase TSH
-dopamine antagonists, amiodarone (ADD)
GOD ADDs to your life, start low to high
Interpreting Thyroid Function Tests
Hypothyroidism SX
- weight GAIN
- low energy
- depression
- COLD intolerance
- constipation
- bradycardia
- dry skin
most common: hashimoto’s
Drug-induced Hypothyroidism
- Amiodarone
- Carbamazepine
- Interferons
- Lithium
- Tyrosine kinase inhibitors (sunitinib, sorafenib)
CAL IT!
Hypothyroidism TX options
- T4 replacement: levothyroxine (synthetic, man made)
- T3 replacement: liothyronine (Cytomel)
- T3/T4 combination: Armour Thyroid (FROM PIGS, DONT USE IF PORK ALLERGY)
Levothyroxine (Synthroid): dose, CI, warning, how to take
Drug of choice
-1.6 ug/kg/day (elderly need 20-25% less, >50 yo)
-cardiac diseases: 12.5-25 ug daily
-Warning: NOT for obesity or weight loss, toxicity
-CI: adrenal insufficiency, glucocorticoid therapy initiation
-with water, same time each day, 30-60 min before bfast or 3 hr after din, don’t crush/chew
-brand name recommended (or same generic preparation)
Levothyroxine Titration
- In increments of 12.5-25 ug
- Titrate every 4-6 weeks until TSH is normal, then 4-6 months, then yearly
Check Free T4 for: selected patients
- poor absorption
- Pregnancy
- central hypothyroidism (defect in pituitary production of TSH)
T4 for PPP
Liothyronine (Cytomel)
- 25 mcg PO daily
- Titrate in 12.5-25 mcg increments
- Maintenance: 25-75 mcg PO daily
- Titrate Q 1-2 weeks
Armour Thyroid (desiccated thyroid)
**1 grain = 60 mg = 100 mcg levothyroxine++
- Initial: 15-30 mg PO daily (15 mg in CAD patients)
- Titrate by 15 mg q2-3 weeks
- Maintenance: 60-120 mg/day
SE: increase rate of hypersensitivity
Medications to separate by 4 hours
- Medications containing polyvalent cations (iron, calcium, aluminum)
- Bile-acid sequestrants
- Sucralfate
- Orlistat
- Sevelamer
- Sodium polystyrene sulfonate
MOB triple SSS
Medications to separate by 3 hours
Patiromer
pat is 3
Medications to separate by 2 hours
Lanthanum
Effect of hypothyroidism on medications
Digoxin: decrease doses achieve therapeutic levels
Warfarin: increase doses needed due to slowed catabolism of clotting
BUT IF YOU FIX IT OPPOSITE
Hyperthyroidism SX
- weight LOSS
- tachycardia, palp
- insomnia
- nervous, anxiety
- HEAT intolerance
- diarrhea
- tremor, weak muscles
- onyvholysis (nails), bulging eyes, goiter**
most common cause is grave’s
Hyperthyroidism TX
Thioamide: PTU and MMI
Radioactive iodine
Surgery
Propylthiouracil (PTU), Methimazole (MMI) MOAs
-Block synthesis of thyroid hormone (BOTH)
-PTU (ONLY) blocks peripheral conversion of T4 to T3
PTU and MMI dosing
MMI
-Initial: 15-40 mg/day PO 1-2x/day
-Main: 5-15 mg/day
PTU
-Initial: 50-150 mg PO TID
-Main: 50 mg PO BID-TID
PTU/MMI AE
Rash
Pancreatitis
*Agranulocytosis
Arthralgias and lupus-like syndrome
*Vasculitis
*GI effects
*Hepatotoxicity: children are more susceptible to hepatotoxic reactions from PTU than are adults
GAAV the RPH
PTU/MMI Monitoring
-FT4 and total T3 should be obtained 2–6 weeks after initiation
-Once euthyroid, dose of MMI can be decreased by 30%–50%, testing repeated in 4–6 wk
-Then test every 2-3 mo, if longterm >18mo then every 6 mo
-If med is primary therapy, should be continued for 12–18 mo, then d/c if TSH and TRAb levels are normal at that time
-AST/ALT/Alk Phos/WBC/ANC labs
CBC and LFTs
Adjunctive therapies: Beta Blockers
-Blocks T4 to T3
*Atenolol: 25-50 mg a day
*Propranolol: 20-40 mg a day
SE: hypotension, bradycardia, av block (BP HR EKG)
Adjunctive therapies: Iodides
- dilute in full glass of liquid
- take with food or milk
SE: HS rxn, salivary gland swelling, metallic taste or mouth/throat irritation, sore gums/teeth, diarrhea
SMD HP (contra: preg)
CI: iodine HS, pregnancy/BF
10 days prior to surgery OR 3-7 days after radiotherapy
Myxedema Coma TX
T4 200-400 ug IV a
AND
hydrocortisone 100 mg IV q8h
AND
supportive, treat underlying disorder
Thyroid Storm TX
-103+ fever, sweat, tachy, A fib, dehydration, delirium
PTU preferred, 500-1000 mg load then 250 mg q4h
+ BB + iodine + steroid
