Chapter 45: Thyroid Disorders; Chapter 46: Steroid/ Autoimmune Flashcards
Main fuction of the thyroid gland
It produces thyroid hormones, which regulates metabolism including many processes that is needed to maintain life (cardiac/ nervous system func, body temp, etc)
Pathophysiology of thyroid hormones, what are they?
Two main hormones: triiodothyronine (T3) and thyroxine (T4). The thyroid gland is the only organ that absorbs iodine! Which is needed to make T3 and T4.
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T4 breaks down to T3 (T3 is more potent but has shorter half life)
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Thyroid Stimulating Hormone (TSH) is secreted by the pituitary gland and it regluates thyroid hormones thru a negative feedback loop. When levels of circulating/ free T4 increases, it inhibits secretion of TSH. and less TSH will lead to less T4. Free T4 (FT4) is the unbound active form that is monitored in ppl with thyroid disorders
Hypothyroidism
HYPOTHYROIDISM: General info/ how is it diagnosis (lab parameters)
- Deficiency/ low in T4 and elevated/high TSH
- Most common cause of hypothyroidism = hashimoto’s (an autoimmune disorder where body attacks thyroid)
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Myxedema coma is an uncommon but potentially fatal complication; life threatening issues characterized by poor circulation/ hypothermia/ hypometabo = inital tx is IV levothyroxine
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Labs: LOW free T4 (norm range is 0.9-2.3); HIGH TSH (norm range 0.3-3)
Hypothyroidism
S/SX of Hypothyroidism
- cold intolerence/ sensitivity
- dry skin
- fatigue
- muscle cramps
- voice changes
- consitpation
- weight gain
- goiter
- myalgias
- depression
- bradycardia
- loss of hair
- menorrhagia (heavy period)
- memory impariment
Hypothyroidism
Select Drugs and Conditions That Can Cause Hypothyroidism
Remember: ITALC
I - Interferons (can also cause hyper)
T - Tyrosine kinase inhibitors (ie. sunitinib)
A - Aminodarone (can also cause hyper)
L - Lithium
C - Carbamazepine
C - Conditions: hashimoto’s, iodine def
Hypothryoidism
Drug Monitoring / monitoring of hypothyroidism
- TSH is the primary test to monitor thyroid fuction in ppl recieving thyroid hormone replacement. It should be monitored q 4-6 weeks until levels are normal… and then 4-6 mts later and then yearly.
- Too high of thyroid hormone can = afib and fractures and older ppl
- Occasionally T4 labs will also be ordered with TSH (but TSH is main one!
Hypothyroidism
Drug treatment for Hypothyroidism/ what is the drug choice?
- Levothyroxine (T4) is the drug of choice for hypothyroidism.
- However, some patients reported feeling better using other thyroid med/ formulation like Liothronine (T3) aka Cytomel OR a desiccated throid T3 and T4 (Armour Thyroid)
- Iodine may also help (from salt) but those on restricted salt diet should get iodine from multivitamin
Hypothyroidism Treatment
Levothyroxine (T4): Brands, general dosing?Notes on oral vs IV
- Brands: Synthroid, Levoxyl, Unithroid
- Full replacement dose: 1.6mcg/kg/day
- If patient has CAD, start with 12.5-25 mcg QD
- This is the drug of choice! check the therapeutic equivalance of generic to brand in ORANGE BOOK
- Levothyroxine (PO): take with water, at least 60mins before breakfast or at bedtime at least 3 hrs after meal. Tabs colors are standard! and do not change from manufacture.. we also want ot try to keep patient on same dose..so ask provider if refill pills look different!
- Levothyroxine (IV): IV:PO = 0.75:1
Hypothryoidism Treatment
Thyroid Desiccated USP ( T3 and T4): Brand, dosing, notes
- Brand: Armour Thyroid
- start: 15-30 mcg, usual daily dose: 60-120mcg QD
- Contains both T3 and T4; less predictable potency and stability
Hypothryoidism Treatment
Liothyronine (T3): Brand, dosing, notes
- Brand: Cytomel
- start: 25mcg, usual daily dose: 27-75mcg QD
- Shorter half life can cause flucuation of T3
Hypothyroidism
Hypothyroidism Treatment (levothyroxine. liothyronine, armour thyroid): Boxed warning, warning, SE, monitoring, Notes
- Boxed Warning: toxic when use as weight reduction!
- Warnings: decrease dose in cardiovascular disease and ppl with lower bone density
- SEs: hyperthyroid SEs like increased HR, arrthy, weight loss
- Monitoring: TSH q 4-6 wks until levels are normal then 4-6 months, then yearly
- Note: highly protein bounded!
Levothyroxine Tablet Colors
Remember this: Orangutans Will Vomit On You Right Before They Become Large Proud Giants.
- O: orange - 25mcg
- W: White - 50mcg
- V: Violet - 75mcg
- O: Olive - 88mcg
- Y: yellow - 100 mcg
- R: Rose - 112mcg
- B: Brown - 125mcg
- T: Turquoise - 137 mcg
- B: Blue - 150mcg
- L: Liliac - 175mcg
- P: Pink - 200mcg
- G: Green - 300mcg
Hypothryoidism
Drug interactions that will decrease the effects of thyroid replacement hormone treatment!
- Antiacids and cations containing: iron, calcium, aluminum, or magnesium, muitlvitamins (containing iron, folate), cholestyramine, sevelamer and sucralfate: SEPERATE THESE FROM LEVOTHYROXINE BY 4 HRS
- b blockers, aminodarone, SSRI, estrogen can decrease level
Hypothryoidism
Thyroid replacement can change the concentration of these drugs
- increase effects of warfarin!
- decrease effects of theophylline
Hyperthyroidism
What is Hyperthyroidism and what are the S/SX?
- Overactive thyroid aka thyrotoxicosis
- FT4 is HIGH and TSH is LOW
- Left untreated? and lead to tachy, arrthy, HF, osteoprosis
- S/SX: heat intolerence/ increased sweat, weight loss, anxiety, tachy, fatigue, frequent diarrhea or bowel movement, tremors, insomia, thin hair, goiter (possible), exophthalmos (protrusion eyeballs), light or absent periods
Hyperthyroidism
Hyperthyroidism : causes
- Most common cause is Grave’s Disease an autoimmune (like Hashimoto’s) but in this case, antibodies do not attack thyroid but rather overstimulate the thyroid to produce too much T4
- Drug induced hyperthyroidism include iodine, amiodarone, interferons, or exposure to contrast media
Hyperthyroidism
Treatment for Hyperthyroidism
- Antithyroid medications (it takes 1-3 months at high dose to control symp then patient can do dose reduction)
- Destroying part of gland with radioactive iodine
- Surgery
- Beta Blocker for symp control of tachy, termors
Hyperthyroidism Treatment
Thionamides: MOA, Drug names in this class, dose notes
- MOA: inhibits synthesis of thyroid hormones by blocking oxidation of iodine in thyroid gland… PTU also inhibits conversion of T4 to T3
- Propylthiouracil (PTU): 50-150mg Q8h… This drug is perferred in thyroid storm!!! and in pregnancy this is the pref drug in 1st trimester
- Methimazole: 5-15mg QD; this is the pref drug choice d/t lower risk of liver issues but except in thyroid strom! this drug can be used in 2nd-3rd trimester
Hyperthyroidism
Thionamides: BW (PTU), general warnings
- BW (PTU): severe liver injury / failure!!! In preg? 1st trimester use PTU BUT in 2-3rd trimester use Methimazole
- Warning: hepatoxicity (monitor: or abdominal pain, yellow skin and eyes, dark urine, nausea), bone marrow suppression, DILE
Hyperthyroidism Treatment
Iodides: MOA, SEs
These are liquid Iodine solutions
- MOA: temporarily inhibt secretion of T4 and T3 levels…reduced for a few weeks but effects will not be maintained.
- SEs: rash, metallic taste, sore gum/mouth
Hypertyroidism
Potassium Iodine Use After Exposure to Radiation
Potassium Iodide (KI) blocks the accumulation of radioactive iodine in the thyroid gland thur preventing thyroid cancer - should be taken ASAP after radiation!
Hyperthyroidism
Thyroid Strom: What is it? Causes? What are the S/SX??
- Life threatening medical condition!!! characterized by decompensated hyperthyroidism.
- Causes: infection, trauma, surgery, radioactive iodine, or not taking antithyroid med
- S/SX: Fever (>103F), tachy, tachypnea, sweating, dehydaration, coma, physcosis, delulu, agitation
Drug treatment for Thyroid Storm
- Antithyroid med: PTU is preferred: LD 500-1000mg then 250mg Q4h PLUS
- Inorganic iodide therapy (SSKI) 5 drops or Lugol’s solution 4-8 drops PLUS
- Beta Blocker (propanolol 40-80mg ) PLUS
- Systemic steroid (dex 2-4mg) PLUS
- Aggressive cooling with APAP and cooling blankets / otjer suppoettive measures
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NEED ALL 5!!!! antithyroid, iodide, BBlocker, Steroid, Cooling
Thyroid Disease In Pregnancy: what are the complications? Hypothyroidism? Hyperthyroidism? What to do in these cases?
Complications: loss of preg, prematire birth, low birth weight
1. Hypothyroidism: levothyroxine is safe and is the reccomended regimen. Will need a 30-50% dose increase throughout course of pregnancy
2. Hyperthyroidism: Drug is based on where she is in trimester. 1st: PTU, then switch to Methimazole during 2-3rd trimester
CHAPTER 46: SYSTEMIC STEROIDS + AUTOIMMUNE CONDITIONS
Systemic Steroids: What are they/ what are they used for?
- There are several different drugs used to treat inflammation including NSAIDs and Steroids (focusing on steroids in this chapter)
- Steroids are used for various inflammatory conditions (ir. RA, psoriasis, asthma/ copd exacerbation), adrenal insufficiency (see the steroid it produces below)!
- 2 endogenous steroids that require replacements are: cortisol (replaced by giving any steriods) and Aldosterone (replaced by giving fludrocortisone)
Talk about Fludrocortisone: What does it do? what is it used for?
- It mimics Aldosterone as it has mineralocortisone activity, which maintain balance of H20 and electrolytes and keep BP stable.
- FDA approved for Addison’s Disease
- Off label use for orthostatic hypotension
Talk about the other steroids like prednisone, hydrocortisone: What does it do? what is it used for?
- These steroids have more glucocorticoid activities = has more anti-inflammatory effect! (this chapter focuses more on glucocortico steroids!)
- These steroids can cause the adrenal gland to stop producing cortisol d/t feedback inhibition. This is called suppression of the hypothalamic pituiitary adrenal axis
- When long term steroids are d/c, they need to be tapered off to give adrenal glad time to resume cortisol production
Cushing’s Syndrome: Talk about it! What happens (S/Sx)?
- When the adrenal gland produces too much cortisol or if exogenous (ie. taken as drug) steroids are taken in doses higher than the normal amount of endogenous cortisol
- Long term effects of steroids/ Cushing: glaucoma, fat deposit on face, strech marks (striae), growth retardation, infection/ impaired wound healing, poor bone health, diabetes, acne, GU bleed/ ulcers, psych changes
Addison’s Disease: Talk about it! What happens (S/Sx)?
- Opposite of Cushing’s!
- The adrenal gland is NOT making enough cortisol!
- If exogenous steroids (medication) is stopped suddenly.. it can cause “Addisonian Crisis” = volume deplete and hypotension…which can be fatal
Systemic Steroids (PO, IV) Dose Equivalance
To remember least to highest potency?: Cute Hot Pharmacist and Physicians Marry Together & Deliver Babies
Case Scenario
AS is a 30 y/o F who presents to hospital with an acute flare of Crohn’s Disease. She was started on Solu-Medrol 40mg IV BID. The medical team wants to transition her to oral prednisone at an equivalant dose. Assuming the IV:PO of Solu-Medrol is 1:1. What is the equivalent daily dose?
- Solu-Medrol is Methylprednisolone! and the equivulant dosing is 4mg and prednisone is 5mg
- Answer = 100mg prednisone TDD
Treating Acute Inflammation with Steroids: an example of Medrol therapy pack
