Thyroid Flashcards
1
Q
Describe levothyroxine use for hypothyroidism
A
- First line for tx of hypothyroidism
- Dosing based on age and cardiac disease
- Decision to start tx based on symptoms; tx life-long for most px
- Should see sx improvement in 2-3 weeks and maximal improvement in 4-6 weeks
- Take in AM on empty stomach or at least 3 h after last meal
- AE = increased HR, tremors, anxiety, diarrhea
- Contraindications = acute MI, untreated adrenal insufficiency
2
Q
Describe liothyronine use for hypothyroidism
A
- Don’t prefer T3 b/c body converts T4 to T3 so just giving T3 will likely make the body forget how to do this conversion; T4 also has longer t1/2
- Can be used as monotherapy or in combo w/ levothyroxine (not 1st line though)
- AE = sx of hyperthyroidism if overtreatment, increased incidence of cardiac events compared to LT4
3
Q
Describe propylthiouracil use for hyperthyroidism
A
- Blocks iodination of tyrosine
- Blocks peripheral conversion of T4 to T3
- Should be tapered over 4-8 weeks then continued for 1-2 years
- AE (*dose dependent) = maculopapular rash, arthralgia, transient fever, GI intolerance
- Contraindication = liver disease
4
Q
Describe methimazole use for hyperthyroidism
A
- 1st line for hyperthyroidism tx in adults, children and 2nd and 3rd trimester of pregnancy
- Blocks iodination of tyrosine
- Should be tapered over 4-8 weeks then continued for 1-2 years
- AE (*dose dependent) = maculopapular rash, arthralgia, transient fever, GI intolerance
5
Q
Describe thyroiditis
A
- Inflammatory damage to the gland; increased release of T4 and T3
- Self-limiting
- Can use beta-blockers to slightly decrease conversion of T4 to T3
6
Q
Describe drug interactions w/ thyroid drugs
A
- Increased T4-binding globulin (so increased T3 and T4 binding in serum) -> estrogens, methadone, perphenazine, SERMs
- Decreased TBG -> androgens, anabolic steroids, glucocorticoids
- TBG inhibitors -> salicylates, furosemide, phenytoin, carbamazepine, NSAIDs, heparin
- Levothyroxine -> TUMS, ranitidine, multivitamin, metformin, carbamazepine
- Wait 4 h between taking levothyroxine and antacids, iron preparations, and calcium supplements
- LT4 increases effect of SSRIs & TCAs
- *Amiodarone can cause hypo or hyperthyroidism (best tx is to d/c amiodarone if possible)
- MMI -> warfarin, digoxin, CYP 2D6 inhibitors (paroxetine, codeine, TCA)
- PTU -> warfarin, digoxin
7
Q
Red flags for thyroid conditions
A
- Signs and sx to report -> chest pain, rapid HR, palpitations, heat intolerance, excessive sweating, increased nervousness, agitation, lethargy
- Myxedema coma (hypothermia, hypotension, hypoventilation, bradycardia) -> consequence of untreated hypothyroidism (more common in elderly)
- Thyroid storm (fever, tachycardia, dehydration, coma, N/V/D) -> consequence of untreated hyperthyroidism
- Poor response to LT4 -> consider compliance, malabsorption, drug interactions, and other diagnosis
- Elderly and post-menopausal w/ hyperthyroid are high risk for complications, so more likely to treat them than younger, healthier px
8
Q
Case specific assessment questions for thyroid conditions
A
- What are your symptoms?
- Hypothyroidism -> fatigue, weakness, constipation, weight gain w/ poor appetite
- Hyperthyroidism -> hyperactivity, irritability, diarrhea, goiter
- Hypothyroidism in elderly -> fewer sx; memory loss, confusion, weight gain, dry skin; specific signs = non-joint pain, falling, ataxia (similar to being drunk)
9
Q
General non-pharms for thyroid
A
Smoking cessation (decreases response to MMI and PTU)
10
Q
General monitoring for thyroid
A
- Always monitor TSH b/c most sensitive marker
- Can also measure free T4 (not free T3 b/c can be affected by other sources)
- Hypothyroidism -> measure TSH and FT4 1 month after initiating or changing dose & every 6-8 weeks until stable; measure in the morning; then measure yearly
- Pt should monitor signs and signs weekly (improve in 2-3 weeks; skin change in 3-6 months)
- Hypothyroidism in pregnancy -> measure TSH every 4 weeks in 1st half of pregnancy, then every week in weeks 26-32
- Hyperthyroidism -> monitor TSH, CBC, and LFTs every 4 weeks until euthyroid, then every 6-12 months after remission
- For px on levothyroxine, monitor TSH 6-8 weeks after interacting drugs are initiated, changed, or discontinued
- For px on propylthiouracil, watch for signs of liver disease (fatigue, abdominal pain, easy bruising, yellowing of eyes/ skin)
11
Q
General follow up for thyroid conditions
A
- Hypothyroidism -> pharmacist follow up in 1 week to see if sx improving and if pt is adherent (takes 2-3 weeks to see sx improvement)
- Hyperthyroidism -> pharmacist follow up in 3 days to see if sx improving and pt is adherent (takes days to see improvement w/ MMI and PTU)
12
Q
Describe monitoring for a new hypothyroidism therapy
A
- Monitor for sx improvement weekly and SE of medication daily
- SE of levothyroxine = increased HR, anxiety, diarrhea (titration can minimize SE)
- Sx of hypothyroidism = fatigue, weight gain, cold intolerance, dry skin/hair, constipation (tailor to what they tell you in assessment)
13
Q
Describe when to go to a Dr for a new hypothyroidism therapy
A
- Go to doctor in 6-8 weeks to get levels rechecked. At that point they will decide if a dose increase is needed.
- Should see some sx improvement in 2 weeks
14
Q
Describe when to go to emergency for a new hypothyroidism therapy
A
Go to emergency if sx worsen and become very severe
15
Q
Describe non pharms for a new hypothyroidism therapy
A
- Make sure to take dose at the same time each day
- Preferred 30-60 min before breakfast or HS at least 3 hr after dinner
- Space out from certain foods (list on pg. 56)
