Thyroid

Question 1

Describe levothyroxine use for hypothyroidism

Answer 1

• 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

Question 2

Describe liothyronine use for hypothyroidism

Answer 2

• 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

Question 3

Describe propylthiouracil use for hyperthyroidism

Answer 3

• 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

Question 4

Describe methimazole use for hyperthyroidism

Answer 4

• 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

Question 5

Describe thyroiditis

Answer 5

• 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

Question 6

Describe drug interactions w/ thyroid drugs

Answer 6

• 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

Question 7

Red flags for thyroid conditions

Answer 7

• 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

Question 8

Case specific assessment questions for thyroid conditions

Answer 8

• 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)

Question 9

General non-pharms for thyroid

Answer 9

Smoking cessation (decreases response to MMI and PTU)

Question 10

General monitoring for thyroid

Answer 10

• 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)

Question 11

General follow up for thyroid conditions

Answer 11

• 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)

Question 12

Describe monitoring for a new hypothyroidism therapy

Answer 12

• 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)

Question 13

Describe when to go to a Dr for a new hypothyroidism therapy

Answer 13

• 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

Question 14

Describe when to go to emergency for a new hypothyroidism therapy

Answer 14

Go to emergency if sx worsen and become very severe

Question 15

Describe non pharms for a new hypothyroidism therapy

Answer 15

• 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)

Question 16

Describe follow up for a new hypothyroidism therapy

Answer 16

• I will follow up with you 1 to discuss adherence and SE management. We can also discuss how sx are doing, but since you have a follow-up with your Dr. it is best to bring up any concerns with them.
• You should have an appointment with your Dr in 6-8 weeks to re-test your thyroid levels to see if the medication is working

Question 17

Describe monitoring for a new hyperthyroidism therapy

Answer 17

• Monitor for sx improvement weekly and SE of medication daily
• MMI usually preferred over PTU b/c less SE; SE of MMI = skin rash (can use antihistamine or topical steroid), arthralgias (can use tylenol or advil)
• Sx of hyperthyroidism = tremor, heat intolerance, weight loss, menstrual changes, diarrhea, weakness (ultimately whatever they say when you ask them in the assessment)

Question 18

Describe when to go to a Dr for a new hyperthyroidism therapy

Answer 18

• Go to doctor in 6-8 weeks to get levels checked. At that time you should assess if sx are improving.
• Sometimes labs will come back normal but it will take longer for you to see improvement in sx. Should see some sx improvement in 3-4 weeks

Question 19

Describe when to go to emergency for a new hyperthyroidism therapy

Answer 19

Go to emergency if sx worsen and become very severe

Question 20

Describe non pharms for a new hyperthyroidism therapy

Answer 20

Smoking cessation (decreases response to MMI and PTU)

Question 21

Describe follow up for a new hyperthyroidism therapy

Answer 21

• I will follow up with you 1 to discuss adherence and SE management. We can discuss sx improvement, but it would be best to bring that up w/ your Dr at your follow-up appointment.
• You should have an appointment with your Dr in 4-6 weeks to re-test your thyroid levels to see if the medication is working

Question 22

Describe monitoring for thyroid conditions for a dose change

Answer 22

• Monitor for sx improvement and increased side effects of the medication daily/weekly
• SE of levothyroxine = increased HR, anxiety, diarrhea (can titrate to minimize SE)
• SE of propylthiouracil and methimazole = skin rash, arthralgias

Question 23

Describe when to go to a Dr for thyroid conditions for a dose change

Answer 23

• Go to doctor to get levels re-checked in 6-8 weeks

- Should see some sx improvement after 2 weeks (w/ LT4) or 3-4 weeks (w/ hyperthyroid tx)

Question 24

Describe when to go to emergency for thyroid conditions for a dose change

Answer 24

If sx worsen and become very severe

Question 25

Describe non pharms for thyroid conditions for a dose change

Answer 25

- Take at same time every day - Smoking cessation - Anything else that could potentially help sx? (dress in layers, bathroom hygiene for constipation/diarrhea, moisture for dry skin, exercise and diet for weight gain, etc.)

Question 26

Describe follow up for thyroid conditions for a dose change

Answer 26

- I will follow up with you 1 week to discuss SE management and adherence to medication. Bring up any major concerns about sx w/ your Dr. at the follow-up. - You should have an appointment w/ your Dr in 4-8 weeks (depending if hypo or hyperthyroid) to re-check your thyroid levels to see if the medication is working