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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
Beta Blockers adverse effects
- Hypotension, - bradycardia - fatigue
26
Beta Blockers contraindications
- Uncompensated heart failure | - severe hyperactive airway disease
27
Beta Blockers advantages
- Symptomatic relief - rapid onset (hours) - useful in acute thyrotoxic states
28
Beta Blockers disadvantages
- Does not correct hyperthyroidism | - variable tolerability of beta blockers
29
Beta Blockers pearls
Alternative to beta blocker if cannot be used is diltiazem 120mg every 8 hours or clonidine 150mcg twice daily
30
Beta Blockers used for hyperthyroidism
- Propranolol - Nadolol - Atenolol - Metoprolol tartrate
31
Radioactive Iodine (RAI) indication
- Grave’s disease - toxic autonomous nodules - toxic multinodular disease - comorbidities increasing surgical risks - planning a pregnancy in the future - liver disease - thyroid ablation
32
Radioactive Iodine (RAI) MOA
Disrupts hormone synthesis by incorporating into thyroid hormones and thyroglobulin -> cellular necrosis and breakdown of follicles
33
Radioactive Iodine (RAI) adverse effects
- Metallic taste - chest pain - neck soreness and swelling - nausea - vomiting - hives - pruritus - tachycardia
34
Radioactive Iodine (RAI) contraindications
- Pregnancy - lactation - thyroid cancer
35
Radioactive Iodine (RAI) monitoring
FT4 and TT3 1-2 months and every 4-6 weeks after RAI until euthyroid, then annual thyroid function test
36
Radioactive Iodine (RAI) advantages
- “Cures” hyperthyroidism - more immediate results - avoids surgery - avoids A/E with drug therapy
37
Radioactive Iodine (RAI) disadvantages
- 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
Radioactive Iodine (RAI) pearls
- 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
Surgery (Thyroidectomy) indication
- 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
Surgery (Thyroidectomy) procedure
- 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
Surgery (Thyroidectomy) complications
- Hypothyroidism (49%) - hypoparathyroidism (3.9%) - vocal cord abnormalities (5.4%)
42
Surgery (Thyroidectomy) monitoring
- After surgery: Calcium, parathyroid hormone - 6-8 weeks post surgery: TSH - Annually: TSH
43
Surgery (Thyroidectomy) advantages
- Rapid - effective - “cures” hyperthyroid - useful in patients with large goiter - avoids radioactivity exposure and long-term A/E with thioamides
44
Surgery (Thyroidectomy) disadvantages
- Invasive - potential complications - cost - permanent hypothyroidism (0.6-17.9%) - lifelong treatment with T4 - pain/scarring
45
Clinical presentation: thyroid storm
- decompensated thyrotoxicosis - high fever (>103F) - tachycardia - tachypnea - afib - CHF - dehydration - delirium - coma - nausea - vomiting - diarrhea (symptoms may persist up to 8 days)
46
Precipitating factors: thyroid storm
- infection - trauma - surgery - RAI treatment - withdrawal from antithyroid drugs
47
Thyroid Storm Treatment
- PTU or MMI - Potassium iodide - Propranolol or esmolol - Hydrocortisone or dexamethasone
48
clinical presentation of hypothyroidism
- intolerance to cold - constipation - muscle ache / weakness - hair loss - depression - weight gain
49
What are lab abnormalities with hypothyroidism?
- High TSH - Low TT4 - Low FT4 - Low TT3
50
When should patients with high TSH be treated?
when TSH levels >5 mIU/L with symptoms or >10 mIU/L without symptoms
51
What is one thing to note about lab values when considering hypothyroidism?
Some patients will have low-normal FT4 level at first (compensated hypothyroidism) but as the disease progresses, the level will drop below normal
52
What are the treatment options for hypothyroidism?
- Levothyroxine - Liothyronine - Liotrix / Thyrolar - Natural desiccated thyroid hormone
53
Levothyroxine counseling
Ingestion with food can impair absorption; take at least 30-60 minutes before food or 4 hours after last meal of the day
54
Levothyroxine adverse effects
- Heart failure - angina - MI - arrhythmia - anxiety - dyspnea
55
Levothyroxine advantages
- Stable - pure - predictable potency - inexpensive
56
Levothyroxine disadvantages
Not therapeutically bioequivalent, stay within the same brand
57
Levothyroxine dosing categories
- Uncomplicated adult <50 - > 50 without CVD or < 50 and CVD - > 50 and CVD - Severe hypothyroidism - Subclinical hypothyroidism
58
Levothyroxine dosing: Uncomplicated adult <50
- 1.6 mcg/kg/day | - Dose titration by 25 mcg every 6-8 weeks; usual doses < 200 mcg/day
59
Levothyroxine dosing: > 50 without CVD or < 50 and CVD
- 25-50 mcg/day | - Dose titration by 12.5-25 mcg/day every 6-8 weeks as tolerated
60
Levothyroxine dosing: > 50 and CVD
- Initial 12.5-25 mcg/day | - Dose titration by 12.5-25 mcg/day every 4-6 weeks as tolerated
61
Levothyroxine dosing: Severe hypothyroidism
- Initial 12.5-25 mcg/day | - Dose titration by 25 mcg every 2-4 weeks as tolerated
62
Levothyroxine dosing: Subclinical hypothyroidism
1 mcg/kg/day
63
Levothyroxine monitoring
Check TSH levels 6-8 weeks until normalized and 8-12 weeks after dosage change; yearly thereafter
64
Levothyroxine pearls
- 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
Liothyronine brand names
- Cytomel | - Triostat
66
Liothyronine adverse effects
- Arrhythmia - tachycardia - hypotension
67
Liothyronine advantages
- Stable - pure - predictable dosing - rapid onset (hours)
68
Liothyronine disadvantages
- Greater potential for cardiac A/E - multiple daily dosing - higher cost
69
Liothyronine monitoring
- T3 - TSH - heart rate - blood pressure - 8 weeks after initiation and dose change and then yearly
70
Liotrix (Thyrolar)
Levothyroxine/Liothyronine T3T4
71
Liotrix adverse effects
- Increased blood pressure - arrhythmia - anxiety - alopecia - changes in menstrual cycle - weight loss - thyrotoxicosis with high T3
72
Liotrix advantages
- Stable - pure - predictable potency
73
Liotrix pearls
- Trials have shown that the combination is no better than T4 monotherapy - not recommended in pregnancy
74
Liotrix monitoring
- T4 - TSH - heart rate - blood pressure - 8 weeks after initiation and dose change and then yearly
75
Natural / Desiccated Thyroid adverse effects
Allergic reaction
76
Natural / Desiccated Thyroid pearls
Not recommended by the American Association of Clinical Endocrinologists because variable amount of iodine, thyroid hormones and potency
77
Natural / Desiccated Thyroid monitoring
- T4 - TSH - heart rate - blood pressure - 8 weeks after initiation and dose change and then yearly
78
clinical presentation of myxedema coma
- Decompensated hypothyroidism with symptoms - hypothermia - delirium - coma
79
Myxedema coma treatment options
- 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
Warfarin and thyroid abnormalities scenarios
- hyperthyroidism require less warfarin (increased warfarin catabolism) - hypothyroidism require more warfarin (decreased warfarin catabolism)
81
Digoxin and thyroid abnormalities scenarios
- hyperthyroidism require more digoxin (resistant to digoxin) - hypothyroidism require less digoxin (increased sensitivity to digoxin)
82
Insulin and thyroid abnormalities scenarios
Insulin degradation can be delayed leading to lower insulin doses
83
What can impair absorption of levothyroxin?
- Taking the medication with food - Cholestyramine - Calcium carbonate - Sucralfate - Aluminum hydroxide - Ferrous sulfate - Histamine blockers - Proton pump inhibitors - Dietary fiber supplements
84
What can you do to optimize levothyroxin absorption based on the factors that can decrease absorption?
Separate drug administration by 4 hours
85
What are the causes of drug-induced thyroid disease?
- lithium | - amiodarone
86
Drug-induced thyroid disease: Lithium
- 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
Drug-induced thyroid disease: Amiodarone
- Can cause hypo- or hyperthyroidism because of its high iodine content
88
Drug-induced thyroid disease: Amiodarone Hypothyroidism
- may occur at any point and not dose related - normal FT4 and elevated TSH - treat with levothyroxine
89
Drug-induced thyroid disease: Amiodarone Hyperthyroidism
- occurs early / suddenly - elevated hormone level and undetectable TSH - Type I and Type II
90
Drug-induced thyroid disease: Amiodarone Hyperthyroidism Type I
- 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
Drug-induced thyroid disease: Amiodarone Hyperthyroidism Type II
- 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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