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OU Module Endo Fall 2018 > Pharmacotherapy of Thyroid Medications Exam 1 > Flashcards

Pharmacotherapy of Thyroid Medications Exam 1 Flashcards

1
Q

clinical presentation of hyperthyroidism

A
  • Nervousness
  • Sweating
  • Palpitations
  • Fatigue / weakness
  • Oligomenorrhea
  • Loss of libido
  • Emotional lability
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2
Q

What are signs / symptoms upon a physical exam that could denote hyperthyroidism?

A
  • high blood pressure
  • high heart rate
  • thyroid palpitation and auscultation to determine size, nodularity and vascularity
  • eye exam
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3
Q

What are lab abnormalities with hyperthyroidism?

A
  • Low TSH
  • High TT4
  • High FT4
  • High TT3
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4
Q

What are additional tests that can be done to confirm hyperthyroidism?

A
  • thyrotropin receptor antibodies
  • radioactive iodine uptake
  • measurement of thyroidal blood flow on ultrasonagraphy
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5
Q

What are the treatment options for hyperthyroidism?

A
  • Thioamides
  • Potassium Iodide
  • Beta Blockers
  • Radioactive Iodine (RAI)
  • Surgery (Thyroidectomy)
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6
Q

Thioamides indication

A
  • mild hyperthyroidism
  • preoperative preparation for thyroidectomy
  • pretreatment for RAI in elderly or patients with cardiac disease
  • elderly
  • thyroid storm
  • Grave’s disease
  • pregnancy
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7
Q

Thioamides MOA

A

Inhibits synthesis of thyroid hormones by inhibiting coupling of MIT and DIT and formation of T3 and T4; propylthiouracil also inhibits the peripheral conversion of T4 to T3

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8
Q

Thioamides monitoring

A
  • complete blood count (CBC) to evaluate neutropenia and
  • liver function test (LFT) due to hepatotoxic risk
  • T3, T4, and TSH 4 weeks after initiation and at 8 week intervals until euthyroid levels achieved, then every 6 months
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9
Q

Thioamides adverse effects

A
  • rash
  • arthralgias
  • drowsiness
  • flulike symptoms
  • abdominal pain
  • GI intolerance in 4-5% of
    patients
  • edema
  • headache
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10
Q

Thioamides severe adverse effects

A
  • Agranulocytosis
  • Hepatotoxicity
  • Fever
  • Pneumonitis
  • DO NOT rechallenge the patient if any of this occurs
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11
Q

Thioamides severe adverse effects: Agranulocytosis

A
  • fever, malaise, gingivitis, oropharyngeal infection, and granulocyte count <250mm3
  • more common in patients >40 yoa who are receiving MMI doses >40mg/day or PTU doses >400mg/day
  • typically occurs during 1st three months of therapy
  • after stopping therapy, improvement seen withing a few days to a few weeks
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12
Q

Thioamides severe adverse effects: Hepatotoxicity

A

Typically occurs during 1st three months of therapy

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13
Q

Thioamides advantages

A
  • Noninvasive
  • lower initial cost (~$45-90)
  • low risk of permanent hypothyroidism and lifelong treatment
  • avoidance of surgery and radioactivity exposure
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14
Q

Thioamides disadvantages

A
  • Low cure rate
  • adverse drug reactions
  • drug adherence
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15
Q

Thioamides pearls

A
  • PTU is preferred in 1st trimester of pregnancy or lactation
  • PTU drug of choice in thyroid storm because of the earlier onset of action
  • Effect can be delayed by weeks since is blocks production of new hormones
  • Clinical improvement usually seen within 3 months
  • Discontinue therapy after 12-18 months if values normalize
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16
Q

Potassium Iodide indication

A
  • Preparation for surgery
  • quickly attain euthyroid state in patients severely thyrotoxic with cardiac compromise
  • to inhibit thyroid hormone release following RAI
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17
Q

Potassium Iodide MOA

A

Inhibits secretion of thyroid hormone

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18
Q

Potassium Iodide monitoring

A

Thyroid function (T3, T4, TSH) 6 weeks after initiation and every 8 weeks until euthyroid and then annually

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19
Q

Potassium Iodide adverse effects

A
  • Hypersensitivity reactions
  • salivary gland swelling
  • “iodism” (metallic taste, burning mouth and throat, sore teeth and gums)
  • stomach upset
  • diarrhea
  • gynecomastia
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20
Q

Potassium Iodide contraindications

A
  • Hypersensitivity

- nodular thyroid condition with heart disease

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21
Q

Potassium Iodide advantages

A

Rapid and effective in severe thyrotoxicosis and rapid onset (24-48 hours)

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22
Q

Potassium Iodide disadvantages

A

Maximal effect is only sustained for 10-15 days

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23
Q

Beta Blockers indication

A
  • Adjunct therapy for relief of symptoms of palpitations, anxiety, tremor and heat tolerance
  • adjunct therapy for Grave’s disease, toxic nodules, preparation for surgery
  • used in thyroid storm
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24
Q

Beta Blockers MOA

A

Inhibits beta adrenergic receptors and partially inhibits peripheral conversion of T4 to T3 at high doses

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25
Q

Beta Blockers adverse effects

A
  • Hypotension,
  • bradycardia
  • fatigue
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26
Q

Beta Blockers contraindications

A
  • Uncompensated heart failure

- severe hyperactive airway disease

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27
Q

Beta Blockers advantages

A
  • Symptomatic relief
  • rapid onset (hours)
  • useful in acute thyrotoxic states
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28
Q

Beta Blockers disadvantages

A
  • Does not correct hyperthyroidism

- variable tolerability of beta blockers

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29
Q

Beta Blockers pearls

A

Alternative to beta blocker if cannot be used is diltiazem 120mg every 8 hours or clonidine 150mcg twice daily

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30
Q

Beta Blockers used for hyperthyroidism

A
  • Propranolol
  • Nadolol
  • Atenolol
  • Metoprolol tartrate
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31
Q

Radioactive Iodine (RAI) indication

A
  • Grave’s disease
  • toxic autonomous nodules
  • toxic multinodular disease
  • comorbidities increasing surgical risks
  • planning a pregnancy in the future
  • liver disease
  • thyroid ablation
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32
Q

Radioactive Iodine (RAI) MOA

A

Disrupts hormone synthesis by incorporating into thyroid hormones and thyroglobulin -> cellular necrosis and breakdown of follicles

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33
Q

Radioactive Iodine (RAI) adverse effects

A
  • Metallic taste
  • chest pain
  • neck soreness and swelling
  • nausea
  • vomiting
  • hives
  • pruritus
  • tachycardia
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34
Q

Radioactive Iodine (RAI) contraindications

A
  • Pregnancy
  • lactation
  • thyroid cancer
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35
Q

Radioactive Iodine (RAI) monitoring

A

FT4 and TT3 1-2 months and every 4-6 weeks after RAI until euthyroid, then annual thyroid function test

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36
Q

Radioactive Iodine (RAI) advantages

A
  • “Cures” hyperthyroidism
  • more immediate results
  • avoids surgery
  • avoids A/E with drug therapy
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37
Q

Radioactive Iodine (RAI) disadvantages

A
  • High risk of subsequent hypothyroidism with lifelong therapy
  • can take up to 1 year for hyperthyroidism to resolve
  • pregnancy must be deferred for 6-12 months
  • increase risk of breast cancer
38
Q

Radioactive Iodine (RAI) pearls

A
  • Treat with thioamides prior to RAI ablation in the elderly and patients with cardiac disease because preformed thyroid hormone will be released causing a transient increase in thyroid hormone levels
  • Can treat with potassium iodide 1-48 hours prior to RAI to help inhibit thyroid hormone release after RAI
  • If patient had thioamides and relapses, recommendation is to treat with RAI
39
Q

Surgery (Thyroidectomy) indication

A
  • Large thyroid gland >80g
  • severe ophthalmopathy, lack of remission on antithyroid drugs, pregnant women, intolerant of thioamides, thyroid malignancies, liver disease, or refuses RAI
40
Q

Surgery (Thyroidectomy) procedure

A
  • Propylthiouracil (PTU) or methimazole (MMI) until euthyroid (usually 6-8 weeks). Then therapy is stopped.
  • Potassium iodide at 50-100mg 3x/day for 10-14 days prior to surgery to decrease the vascularity of the gland and decrease thyroid blood flow.
  • Propranolol can be administered preoperatively and 710 days after surgery to main a pulse rate <90 beats/min
41
Q

Surgery (Thyroidectomy) complications

A
  • Hypothyroidism (49%)
  • hypoparathyroidism (3.9%)
  • vocal cord abnormalities (5.4%)
42
Q

Surgery (Thyroidectomy) monitoring

A
  • After surgery: Calcium, parathyroid hormone
  • 6-8 weeks post surgery: TSH
  • Annually: TSH
43
Q

Surgery (Thyroidectomy) advantages

A
  • Rapid
  • effective
  • “cures” hyperthyroid
  • useful in patients with large goiter
  • avoids radioactivity exposure and long-term A/E with thioamides
44
Q

Surgery (Thyroidectomy) disadvantages

A
  • Invasive
  • potential complications
  • cost
  • permanent hypothyroidism (0.6-17.9%)
  • lifelong treatment with T4
  • pain/scarring
45
Q

Clinical presentation: thyroid storm

A
  • decompensated thyrotoxicosis
  • high fever (>103F)
  • tachycardia
  • tachypnea
  • afib
  • CHF
  • dehydration
  • delirium
  • coma
  • nausea
  • vomiting
  • diarrhea (symptoms may persist up to 8 days)
46
Q

Precipitating factors: thyroid storm

A
  • infection
  • trauma
  • surgery
  • RAI treatment
  • withdrawal from antithyroid drugs
47
Q

Thyroid Storm Treatment

A
  • PTU or MMI
  • Potassium iodide
  • Propranolol or esmolol
  • Hydrocortisone or dexamethasone
48
Q

clinical presentation of hypothyroidism

A
  • intolerance to cold
  • constipation
  • muscle ache / weakness
  • hair loss
  • depression
  • weight gain
49
Q

What are lab abnormalities with hypothyroidism?

A
  • High TSH
  • Low TT4
  • Low FT4
  • Low TT3
50
Q

When should patients with high TSH be treated?

A

when TSH levels >5 mIU/L with symptoms or >10 mIU/L without symptoms

51
Q

What is one thing to note about lab values when considering hypothyroidism?

A

Some patients will have low-normal FT4 level at first (compensated hypothyroidism) but as the disease progresses, the level will drop below normal

52
Q

What are the treatment options for hypothyroidism?

A
  • Levothyroxine
  • Liothyronine
  • Liotrix / Thyrolar
  • Natural desiccated thyroid hormone
53
Q

Levothyroxine counseling

A

Ingestion with food can impair absorption; take at least 30-60 minutes before food or 4 hours after last meal of the day

54
Q

Levothyroxine adverse effects

A
  • Heart failure
  • angina
  • MI
  • arrhythmia
  • anxiety
  • dyspnea
55
Q

Levothyroxine advantages

A
  • Stable
  • pure
  • predictable potency
  • inexpensive
56
Q

Levothyroxine disadvantages

A

Not therapeutically bioequivalent, stay within the same brand

57
Q

Levothyroxine dosing categories

A
  • Uncomplicated adult <50
  • > 50 without CVD or < 50 and CVD
  • > 50 and CVD
  • Severe hypothyroidism
  • Subclinical hypothyroidism
58
Q

Levothyroxine dosing: Uncomplicated adult <50

A
  • 1.6 mcg/kg/day

- Dose titration by 25 mcg every 6-8 weeks; usual doses < 200 mcg/day

59
Q

Levothyroxine dosing: > 50 without CVD or < 50 and CVD

A
  • 25-50 mcg/day

- Dose titration by 12.5-25 mcg/day every 6-8 weeks as tolerated

60
Q

Levothyroxine dosing: > 50 and CVD

A
  • Initial 12.5-25 mcg/day

- Dose titration by 12.5-25 mcg/day every 4-6 weeks as tolerated

61
Q

Levothyroxine dosing: Severe hypothyroidism

A
  • Initial 12.5-25 mcg/day

- Dose titration by 25 mcg every 2-4 weeks as tolerated

62
Q

Levothyroxine dosing: Subclinical hypothyroidism

A

1 mcg/kg/day

63
Q

Levothyroxine monitoring

A

Check TSH levels 6-8 weeks until normalized and 8-12 weeks after dosage change; yearly thereafter

64
Q

Levothyroxine pearls

A
  • May need to lower dose in elderly patients or patients who have lost a significant amount of weight
  • Dose will need to be increased in pregnancy
  • Category >50 yoa and CVD – patients can be very sensitive to the CV effects of therapy – replace very slowly
65
Q

Liothyronine brand names

A
  • Cytomel

- Triostat

66
Q

Liothyronine adverse effects

A
  • Arrhythmia
  • tachycardia
  • hypotension
67
Q

Liothyronine advantages

A
  • Stable
  • pure
  • predictable dosing
  • rapid onset (hours)
68
Q

Liothyronine disadvantages

A
  • Greater potential for cardiac A/E
  • multiple daily dosing
  • higher cost
69
Q

Liothyronine monitoring

A
  • T3
  • TSH
  • heart rate
  • blood pressure
  • 8 weeks after initiation and dose change and then yearly
70
Q

Liotrix (Thyrolar)

A

Levothyroxine/Liothyronine T3T4

71
Q

Liotrix adverse effects

A
  • Increased blood pressure
  • arrhythmia
  • anxiety
  • alopecia
  • changes in menstrual cycle
  • weight loss
  • thyrotoxicosis with high T3
72
Q

Liotrix advantages

A
  • Stable
  • pure
  • predictable potency
73
Q

Liotrix pearls

A
  • Trials have shown that the combination is no better than T4 monotherapy
  • not recommended in pregnancy
74
Q

Liotrix monitoring

A
  • T4
  • TSH
  • heart rate
  • blood pressure
  • 8 weeks after initiation and dose change and then yearly
75
Q

Natural / Desiccated Thyroid adverse effects

A

Allergic reaction

76
Q

Natural / Desiccated Thyroid pearls

A

Not recommended by the American Association of Clinical Endocrinologists because variable amount of iodine, thyroid hormones and potency

77
Q

Natural / Desiccated Thyroid monitoring

A
  • T4
  • TSH
  • heart rate
  • blood pressure
  • 8 weeks after initiation and dose change and then yearly
78
Q

clinical presentation of myxedema coma

A
  • Decompensated hypothyroidism with symptoms
  • hypothermia
  • delirium
  • coma
79
Q

Myxedema coma treatment options

A
  • IV levothyroxine 300-500 mcg followed by 75100 mcg IV until patient stabilizes and can take oral therapy
  • Hydrocortisone 100 mg Q8H until adrenal suppression is ruled out
80
Q

Warfarin and thyroid abnormalities scenarios

A
  • hyperthyroidism require less warfarin (increased warfarin catabolism)
  • hypothyroidism require more warfarin (decreased warfarin catabolism)
81
Q

Digoxin and thyroid abnormalities scenarios

A
  • hyperthyroidism require more digoxin (resistant to digoxin)
  • hypothyroidism require less digoxin (increased sensitivity to digoxin)
82
Q

Insulin and thyroid abnormalities scenarios

A

Insulin degradation can be delayed leading to lower insulin doses

83
Q

What can impair absorption of levothyroxin?

A
  • Taking the medication with food
  • Cholestyramine
  • Calcium carbonate
  • Sucralfate
  • Aluminum hydroxide
  • Ferrous sulfate
  • Histamine blockers
  • Proton pump inhibitors
  • Dietary fiber supplements
84
Q

What can you do to optimize levothyroxin absorption based on the factors that can decrease absorption?

A

Separate drug administration by 4 hours

85
Q

What are the causes of drug-induced thyroid disease?

A
  • lithium

- amiodarone

86
Q

Drug-induced thyroid disease: Lithium

A
  • chronic lithium inhibits release of thyroid hormone
  • lithium induced goiter can cause hypothyroidism
  • most patients with lithium induced hypothyroidism have a prior history of thyroid dysfunction, positive thyroid antibodies or a strong family history of thyroid disease
  • monitor: baseline thyroid function tests and recheck every 6 months
87
Q

Drug-induced thyroid disease: Amiodarone

A
  • Can cause hypo- or hyperthyroidism because of its high iodine content
88
Q

Drug-induced thyroid disease: Amiodarone Hypothyroidism

A
  • may occur at any point and not dose related
  • normal FT4 and elevated TSH
  • treat with levothyroxine
89
Q

Drug-induced thyroid disease: Amiodarone Hyperthyroidism

A
  • occurs early / suddenly
  • elevated hormone level and undetectable TSH
  • Type I and Type II
90
Q

Drug-induced thyroid disease: Amiodarone Hyperthyroidism Type I

A
  • Patients have underlying risk factors for thyroid disease (multinodular goiter) and is related to iodine load (large amounts of thyroid hormone are produced in response to load)
  • Treatment: Methimazole and Potassium
91
Q

Drug-induced thyroid disease: Amiodarone Hyperthyroidism Type II

A
  • Direct destructive type of thyroiditis causing excess release of thyroid hormone
  • Treatment: beta blockers, corticosteroids

OU Module Endo Fall 2018 (27 decks)

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