Pharm - tx of thyroid disorders

Question 1

indication for beta blockers

Answer 1

• adjunctive tx during thyroid storm
• to prep pts for surgery
• to manage pregnant pts w/ thyrotoxicosis in the short term
• primary therapy for thyroiditis or iodine-induced hyperthyroidism

Question 2

beta blocker dosing

Answer 2

• propanolol 20-40 mg QID
• younger pts and severely toxic pts may require 240-280 mg/day in divided doses
• atenolol start w/ 25-50 mg/day and titrate up to 200 mg daily

Question 3

contraindications to use of beta blockers

Answer 3

• decompensated heart failure
• asthma
• COPD
• concomitant MAOi or tricyclic antidepressant use
• 2nd or 3rd degree heart block
• bradycardia
• severe peripheral vascular dz
• Raynaud’s

Question 4

goals of therapy of beta blockers

Answer 4

-decrease the sx of Grave’s

Question 5

what are the 3 treatment options for Graves?

Answer 5

• antithyroid drugs (thioamides)
• radioidodine
• surgery

Question 6

best tx options for pts w/ mild hyperthyroidism, minimal thyroid enlargement, and NO orbitopathy

Answer 6

• radioiodine (w/o thioamide pretreatment or glucocorticoids) OR
• 1-2 year course of thioamides

Question 7

best tx options for pts w/ mild hyperthyroidism, minimal thyroid enlargement, and mild orbitopathy

Answer 7

• radioiodine (w/0 thioamide pretreatment but w/ glucocorticoids) OR
• 1-2 year course of thioamides

Question 8

best tx options for pts w/ more severe hyperthyroidism

Answer 8

• consider definitive therapy w/ radioiodine or surgery OR
• 1-2 year course of thioamides OR
• long term thioamide therapy

Question 9

best tx options for pts w/ moderate to severe orbitopathy

Answer 9

surgery rather than radioiodine w/ glucorcorticoids for definitive therapy

Question 10

thioamide agents

Answer 10

• methimazole

- PTU (propylthiouracil)

Question 11

goals of therapy for thioamide agents

Answer 11

• render the pt euthyroid as quickly and safely as possible

- usually within 3-8 weeks

Question 12

Indication for thioamide agents

Answer 12

• preferred tx for children, pregnant women, and young adults with uncomplicated Grave’s disease
• to control hyperthyroidism (not a cure)
• can be given before surgery or RAI to deplete the thyroid gland of stored hormone to prevent thyroid storm

Question 13

what are the two phases of dosing for thioamides

Answer 13

• initial therapy: achieve eurthyroidism

- maintenance therapy: continued until remission is achieved

Question 14

methimazole dosing

Answer 14

• initial dose is based on the severity of the hyperthyroidism, size of goiter and free T4 level
• small goiter and mild disease (T4 1-1.5 ULN) can be started on 5-10 mg daily
• free T4 1.5 -2 times ULN can be started on 10-20 mg daily
• larger goiters and T4 2-3 times ULN should be started on 20-40 mg daily

Question 15

monitoring parameters of methimazole

Answer 15

-monitor T3 and T4 for response to therapy

Question 16

contraindications to methimazole

Answer 16

-first trimester of pregnancy (category D)

Question 17

initial dosing of PTU

Answer 17

-300-600 mg in divided doses usually 3-4 times per day

Question 18

monitoring parameters of PTU

Answer 18

monitor T3 and T4 for response to therapy

Question 19

major adverse reactions to thioamides

Answer 19

• benign transient leukopenia
• agranulocytosis
• drug induced hepatotoxicity

Question 20

indication for RAIU

Answer 20

• may be considered first choice given lower cost and lower risk of complication that surgery
• Poor surgical candidates, people who don’t response to drug therapy/had ADRs
• those who develop recurrent hyperthyroidism after surg

Question 21

monitoring paramters for RAIU

Answer 21

measure free T4, total T3 and TSH 4-6 weeks after treatment and then at 4-6 week intervals for 6 months

Question 22

goals of therapy for RAIU

Answer 22

to deplete thyroid hormone from gland→decreases risk of hyperthyroidism post-RAI administration and thyroid storm

Question 23

Contraindications to RAIU

Answer 23

• pregnancy/lactating women
• severe/active Grave’s ophthalmopathy
• discouraged/prohibited in patients who can’t follow radiation precautions

Question 24

Given a patient taking thioamides, select the appropriate monitoring for liver toxicity

Answer 24

• baseline CBC/liver enzymes
• routine liver function monitoring not recommended unless patient has hx of liver dz or is at increased risk for hepatitis
• question pt about sx of hepatitis during first few months of therapy

Question 25

Given a patient taking thioamides, select the appropriate monitoring for agranulocytosis

Answer 25

- get baseline CBC - Routine serial WBC not recommended - Pts told to report following sx: rash, fever, sore throat, flu-like symptoms - Differential WBC count ordered during febrile illness and at onset of pharyngitis

Question 26

thyrotoxicosis factitia

Answer 26

Hyperthyroidism produced by the ingestion of exogenous thyroid hormone

Question 27

long-term risks of hyperthyroidism

Answer 27

- results in negative calcium balance, reduced bone density, and increased fracture risk. - tell patients to take 1200-1500mg Ca2+ daily through diet/supplements

Question 28

given a pt with hypothyroidism or subclinical hypothyroidism, select the initial dose based on age, ideal body weight and concomitant conditions

Answer 28

- levothyroxine 1.6-1.7 mcg/kg/day - ideal body weight is best predictor of daily requirements - young healthy adults: start on full dose - 50-60 yo w/o heart dz: start on 50 mcg/day - odler w/ known cardiac dz: 12.5-25 mcg/day titrated up monthly - subclinical: don't need full dose: 25-75 mcg usually is enough

Question 29

given a pregnant woman with thyroid disease, select the appropriate reasons to treat the disease

Answer 29

- Untreated maternal hypothyroidism can lead to increased rate of miscarriage, stillbirths, congenital defects, and mental retardation - Thyrotoxic (hyperthyroidism) women need to be euthyroid before attempting surgery

Question 30

appropriate treatment for hypothyroidism in pregnant women

Answer 30

- If they had it before pregnancy, increase levothyroxine dose by 25-30% upon a missed menstrual cycle or positive pregnancy test and notify their provider→increase from 7 doses/week to 9 doses/week - All those with treated hypothyroidism who are planning a pregnancy should optimize thyroid status before conception (TSH <2.5mIU/L)

Question 31

appropriate treatment for hyperthyroidism in pregnant women

Answer 31

- PTU is preferred for tx in first trimester - Those on methimazole should be switched to PTU if pregnancy confirmed in first trimester→after first trimester, consider switching to methimazole - Both cross the pacenta so to avoid deleterious effects on baby, maintain free T4 level at or just above the upper limits of normal→free T4 and TSH should be monitored every 2-6 weeks

Question 32

goals of therapy for for hypothyroidism in pregnant women

Answer 32

- normalize serum TSH values within trimester-specific pregnancy range - First trimester: 0.1-2.5 mIU/L - Second trimester: 0.2-3.0 mIU/L - Third trimester: 0.3-3.0 mIU/L

Question 33

monitoring parameters for pregnant women

Answer 33

- Monitor TSH and total T4 should be monitored every 4 weeks during the first half of pregnancy - TSH should be checked at least once between 26 and 32 weeks gestation - Adjust doses as needed

Question 34

Given a woman who is planning a pregnancy, select the appropriate reasons for correcting the thyroid status prior to conception

Answer 34

Untreated hypothyroidism can lead to increased rate of miscarriage, stillbirths, congenital defects and mental retardation

Question 35

drugs that can cause drug-induced thyroid dz

Answer 35

- lithium - amiodarone - interferon-alpha

Question 36

lithium

Answer 36

- inhibits release of thyroid hormone from gland so T4 and T3 fall, TSH rises - can get lithium induced goiters - most have family hx of thyroid dz/ positive thyroid abs - ck baseline thyroid fxn before starting lithium - ck every 6 mos

Question 37

amiodarone

Answer 37

- has high iodine content so can get iodine induced hyperthyroidism - can also get hypothyroidism

Question 38

amiodarone induced hyperthyroidism

Answer 38

- occures suddenly - leads to thyrotoxic sx - labs: high thyroid hormone and low TSH - type 1: related to iodine load - type 2: direct destruction of thyroid cells

Question 39

tx of type 1 amiodarone induced hyperthyroidism

Answer 39

- methimazole or PTU to block hormone synthesis | - potassium perchlorate may block iodine uptake by thyroid and deplete iodine stores

Question 40

tx of type 2 amiodarone induced hyperthyroidism

Answer 40

- beta blockers for sx | - prednisone for anti-inflammatory action

Question 41

amiodarone induced hypothyroidism

Answer 41

- not dose related - lab findings: nl T4 and high TSH - tx: T4 replacement

Question 42

interferon alpha induced hyperthyroidism

Answer 42

- graves dz like and hyperthyroid thyroiditis - d/t toxic effect on gland - tx: beta blocker if sx are bothersome

Question 43

interferon alpha induced hyporthyroidism

Answer 43

- risk factors: presence of antithyroid abs before tx, female, Asians - more common than hyperthyroid - tx: start T4 if sx warrant