Antithyroid Flashcards
(207 cards)
1
Q
What are the major indications for the therapeutic use of thyroid hormone?
A
Hormone replacement therapy in hypothyroidism and TSH suppression therapy in thyroid cancer.
2
Q
What type of preparations are used for thyroid hormone therapy?
A
Synthetic preparations of the sodium salts of natural isomers of thyroid hormones.
3
Q
What is the form of levothyroxine sodium available for administration?
A
Tablets, liquid-filled capsules, and lyophilized powder for injection.
4
Q
Where does absorption of levothyroxine occur?
A
In the stomach and small intestine.
5
Q
What is the absorption rate of levothyroxine tablets?
A
Approximately 80%.
6
Q
How does taking levothyroxine on an empty stomach affect its absorption?
A
Increases absorption and reduces variability in TSH levels.
7
Q
When do serum T4 levels peak after oral ingestion of levothyroxine?
A
2-4 hours after ingestion.
8
Q
What is the plasma half-life (t1/2) of levothyroxine?
A
7 days.
9
Q
What should a patient do if they miss a dose of levothyroxine?
A
Take a double dose the next day.
10
Q
How does the T4/T3 ratio in patients taking levothyroxine compare to those with endogenous thyroid function?
A
Slightly higher in patients taking levothyroxine.
11
Q
When are follow-up blood tests typically done after a dosage change of levothyroxine?
A
About 6 weeks after any dosage change.
12
Q
What is the intravenous dosing recommendation for levothyroxine if oral intake is not possible?
A
80% of the patient’s daily oral requirement once daily.
13
Q
What is liothyronine sodium the salt of?
A
T3 (triiodothyronine).
14
Q
What is the absorption rate of liothyronine?
A
Nearly 100%.
15
Q
In what situations is liothyronine used?
A
Myxedema coma or rapid termination of action in thyroid cancer preparation.
16
Q
What are the drawbacks of using liothyronine for chronic replacement therapy?
A
More frequent dosing, higher cost, and transient serum T3 elevations.
17
Q
How does the required daily dose of liothyronine compare to levothyroxine?
A
About one-third of L-T4 to achieve an equivalent TSH level.
18
Q
What is the T3 concentration comparison between normalization of TSH with liothyronine versus levothyroxine?
A
Nearly 2-fold higher serum T3 with liothyronine.
19
Q
What mixture of thyroid hormones is available for therapy?
A
A mixture of levothyroxine and T3 in a 4:1 ratio by weight.
20
Q
What is equivalent in activity to a 60-mg desiccated thyroid tablet?
A
80 µg of levothyroxine.
21
Q
Name one drug that may increase levothyroxine dosage requirements.
A
Aluminum-containing antacids.
22
Q
What factors may impair levothyroxine absorption?
A
Aluminum-containing antacids, bile acid sequestrants, calcium carbonate, food.
23
Q
What is a drug that may decrease levothyroxine dosage requirements?
A
Metformin.
24
Q
What factors may increase thyroxine metabolism?
A
Rifampin, carbamazepine, phenytoin, sertraline.
25
True or False: Advancing age (>65 years) may decrease levothyroxine dosage requirements.
True.
26
What is the hormone of choice for thyroid hormone replacement therapy?
Thyroxine
## Footnote
Due to its consistent potency and prolonged duration of action.
27
Which enzymes convert T4 to T3 in thyroid hormone replacement therapy?
D1 and D2
28
What is the average daily adult full replacement dose of L-T4?
1.7 µg/kg body weight (0.8 µg/lb)
29
On what basis should dosing for thyroid hormone replacement generally be based?
Lean body mass
30
What is the goal of thyroid hormone replacement therapy in hypothyroidism?
Normalize serum TSH or free T4 and relieve symptoms
31
In primary hypothyroidism, what should be monitored instead of free T4?
TSH
32
What is the recommended initial dose for elderly patients or those with cardiac disease?
Subreplacement dose of L-T4 (12.5-50 µg/d)
33
How often can the dose of L-T4 be increased until TSH is normalized?
By 25 µg/d every 6 weeks
34
True or False: Monotherapy with levothyroxine mimics normal physiology.
True
35
What happens to the levothyroxine requirement during pregnancy?
It usually requires a higher dose
36
What adverse effects are associated with overt hypothyroidism during pregnancy?
Increased risk of miscarriage, fetal distress, preterm delivery, and impaired psychoneural and motor development
37
By how much should women increase their levothyroxine dose upon confirming pregnancy?
By 30%
38
When should TSH be measured during pregnancy?
In the first trimester and periodically through to 20 weeks' gestation
39
What is isolated hypothyroxinemia during pregnancy defined by?
Low serum free T4 concentration and normal serum TSH concentration
40
What is the best test to evaluate thyroid status during pregnancy?
TSH
41
What is myxedema coma?
A rare syndrome representing extreme severe, long-standing hypothyroidism
42
What are common precipitating factors of myxedema coma?
* Infection
* Congestive heart failure
* Medical noncompliance
43
What are the cardinal features of myxedema coma?
* Hypothermia
* Respiratory depression
* Decreased consciousness
44
What is the initial loading dose of levothyroxine for myxedema coma?
200-400 µg
45
What is the recommended initial daily dose of levothyroxine for congenitally hypothyroid infants?
10-15 µg/kg
46
What should be monitored after initiating treatment for congenital hypothyroidism?
TSH and free T4 at 2 and 4 weeks, every 1-2 months in the first 6 months, and every 2-3 months until age 3
47
What may impair levothyroxine absorption in infants?
Soy formula
48
What is the goal for free T4 and TSH levels in congenitally hypothyroid infants?
* Free T4 in the upper half of the reference range
* TSH in the lower half
49
True or False: Brand-name and generic levothyroxine are bioequivalent in infants with severe congenital hypothyroidism.
False
50
What are the mainstays of therapy for well-differentiated thyroid cancer?
Surgical thyroidectomy, radioiodine, and levothyroxine to maintain a low TSH
51
Why is TSH suppression important in thyroid cancer treatment?
TSH is a growth factor for thyroid cancer
52
What is a reasonable TSH target range for patients without persistent disease?
Low-normal TSH value
53
What TSH level should be maintained in patients at high risk for recurrence?
Mildly subnormal TSH value (~0.1 mU/L)
54
What are potential risks of TSH suppression therapy?
Osteoporosis and atrial fibrillation
55
What is the most common endocrinopathy?
Nodular thyroid disease
56
What symptoms can thyroid nodules cause?
Neck discomfort, dysphagia, and a choking sensation
57
Are thyroid nodules more common in men or women?
Women
58
What increases the rate of thyroid nodule development?
Exposure to ionizing radiation, especially in childhood
59
What percentage of thyroid nodules that come to medical attention are malignant?
Approximately 5%
60
What should be confirmed by TSH measurement in patients with thyroid nodules?
Most patients with thyroid nodules are euthyroid
61
What are the most useful diagnostic procedures for thyroid nodules?
Ultrasound imaging and fine-needle aspiration biopsy
62
Can levothyroxine be recommended to suppress TSH in euthyroid individuals with thyroid nodules?
No, it cannot be recommended as a general practice
63
When is it appropriate to administer levothyroxine for thyroid nodules?
If the TSH is elevated
64
What are the adverse effects of thyroid hormone typically associated with?
Overtreatment
65
What risks are associated with excess thyroid hormone?
*Atrial fibrillation, especially in the elderly*
*Increased risk of osteoporosis, especially in post-menopausal women*
66
What types of compounds interfere with thyroid hormone activity?
*Antithyroid drugs*
*Iodine inhibitors*
*High concentrations of iodine*
*Radioactive iodine*
*Adjuvant therapy with non-specific drugs*
67
What is the mechanism of action for perchlorate and thiocyanate?
Lodide uptake inhibition
68
What do thionamides do in thyroid hormone synthesis?
Interfere with the organification of iodine
69
Which agents can block hormone release from the thyroid gland?
Li* salts and iodide
70
What can accelerate hepatic metabolism of thyroid hormones?
*Phenobarbital*
*Rifampin*
*Carbamazepine*
*Phenytoin*
*Sertraline*
*Bexarotene*
71
What are the main antithyroid drugs with clinical utility?
The thioureylenes, which belong to the family of thioamides, with propylthiouracil as the prototype.
72
How do antithyroid drugs inhibit thyroid hormone formation?
By interfering with the incorporation of iodine into tyrosyl residues of thyroglobulin and inhibiting the coupling of iodotyrosyl residues to form iodothyronines.
73
What enzyme do antithyroid drugs inhibit?
Peroxidase enzyme.
74
What is the effect of inhibiting hormone synthesis by antithyroid drugs?
Depletion of stores of iodinated thyroglobulin as the protein is hydrolyzed and hormones are released into circulation.
75
What additional effect does propylthiouracil have compared to methimazole?
Partially inhibits the peripheral deiodination of T4 to T3.
76
What is the typical time frame for improvement of the thyrotoxic state after starting antithyroid drugs?
3-6 weeks.
77
What factors influence the clinical response to antithyroid drugs?
The dose of antithyroid drug, size of the goiter, and pretreatment serum T3 concentration.
78
What are the potential consequences of overtreatment with antithyroid drugs?
Hypothyroidism.
79
How often should thyroid function tests be measured after initiating treatment?
Every 2-4 months.
80
What should be done once euthyroidism is established?
Follow-up every 4-6 months.
81
What are the two antithyroid compounds currently used in the U.S.?
* Propylthiouracil (6-n-propylthiouracil)
* Methimazole (1-methyl-2-mercaptoimidazole)
82
What is the mechanism of action of carbimazole?
Its antithyroid action is due to its conversion to methimazole after absorption.
83
What is the absorption time for propylthiouracil after oral dosing?
20-30 minutes.
84
What is the half-life (t1/2) of propylthiouracil in plasma?
75 minutes.
85
What is the half-life (t1/2) of methimazole?
4-6 hours.
86
What is the most serious side effect of antithyroid drugs?
Agranulocytosis.
87
When does agranulocytosis usually occur during therapy?
In the first few weeks or months, but sometimes later.
88
What should patients be instructed to report while on antithyroid drugs?
Development of sore throat or fever.
89
What is a common mild reaction to antithyroid drugs?
Mild urticarial papular rash.
90
What are some less-frequent complications of antithyroid drugs?
* Pain and stiffness in joints
* Paresthesias
* Headache
* Nausea
* Skin pigmentation
* Loss of hair
91
What is the drug of choice for Graves disease?
Methimazole.
92
What is the usual starting dose for methimazole?
15-40 mg per day.
93
What is the usual starting dose for propylthiouracil?
100 mg every 8 hours.
94
What percentage of pregnancies are affected by thyrotoxicosis?
About 0.2%.
95
What is the treatment of choice for thyrotoxicosis in pregnancy?
Antithyroid drugs; radioactive iodine is contraindicated.
96
Which antithyroid drug is usually avoided in the first trimester of pregnancy?
Methimazole.
97
What should be the goal for serum FT4 index during pregnancy?
Upper half of the normal range or slightly elevated.
98
What is a common outcome for Graves disease after delivery?
Relapse or worsening.
99
What is the role of B Adrenergic receptor antagonists in the treatment of thyrotoxicosis?
They antagonize the sympathetic/adrenergic effects, reducing tachycardia, tremor, and relieving palpitations, anxiety, and tension.
## Footnote
Examples include propranolol and atenolol.
100
What is the initial dosage for propranolol in the treatment of thyrotoxicosis?
20-40 mg four times daily.
## Footnote
Atenolol can also be used at 50-100 mg daily.
101
What is the purpose of Ca2+ channel blockers in managing thyrotoxicosis?
To control tachycardia and decrease the incidence of supraventricular tachyarrhythmias.
## Footnote
Examples include diltiazem.
102
How long is short-term treatment with β-adrenergic receptor antagonists or Ca2+ channel blockers typically required?
2-6 weeks.
## Footnote
Treatment should be discontinued once the patient is euthyroid.
103
What type of immunotherapy is used for Graves hyperthyroidism?
B-lymphocyte-depleting agent rituximab combined with methimazole.
## Footnote
This combination prolongs remission of Graves disease.
104
What is thyroid storm?
A life-threatening complication of thyrotoxicosis, usually precipitated by an intercurrent medical problem.
## Footnote
It occurs in untreated or partially treated thyrotoxic patients.
105
What are common precipitating factors for thyroid storm?
* Infections
* Stress
* Trauma
* Surgery
* Diabetic ketoacidosis
* Heart disease
* Rarely, radioactive iodine treatment.
## Footnote
These factors can trigger a thyrotoxic crisis.
106
What are the cardinal features of thyroid storm?
* Fever (>38.5°C)
* Tachycardia out of proportion to fever
* Nausea
* Vomiting
* Diarrhea
* Agitation
* Confusion.
## Footnote
Coma and death may ensue in up to 20% of patients.
107
What is the preferred antithyroid drug in the treatment of thyroid storm?
Propylthiouracil.
## Footnote
It is preferred because it also impairs peripheral conversion of T4 to T3.
108
What is the function of ionic inhibitors in the thyroid gland?
They interfere with the concentration of iodide by the thyroid gland.
## Footnote
Examples include perchlorate and thiocyanate.
109
How does perchlorate function as an ionic inhibitor?
It blocks the entrance of iodide into the thyroid by competitively inhibiting the NIS.
## Footnote
Perchlorate can also be transported by NIS into the thyroid gland.
110
What are the potential risks of excessive perchlorate use?
It can cause fatal aplastic anemia when given in excessive amounts (2-3 g daily).
## Footnote
750 mg daily has been used in the treatment of Graves' disease.
111
What is the effect of lithium on thyroid hormones?
It decreases secretion of T4 and T3, which can cause overt hypothyroidism in some patients.
## Footnote
Lithium is often used for the treatment of mania.
112
What is iodide known for in relation to thyroid gland disorders?
Iodide is the oldest remedy for disorders of the thyroid gland.
## Footnote
Iodide has been used historically to treat various thyroid conditions.
113
How does high concentration of iodide affect thyroid function?
High concentration of iodide can influence several important functions of the thyroid gland.
## Footnote
Specifically, it can inhibit synthesis of iodotyrosines and iodothyronines.
114
What is the Wolff-Chaikoff effect?
The Wolff-Chaikoff effect is when iodide limits its own transport and acutely inhibits the synthesis of iodotyrosines and iodothyronines.
## Footnote
This is a feedback mechanism that prevents excessive thyroid hormone production.
115
What is a significant clinical effect of high plasma iodide concentration?
Inhibition of the release of thyroid hormone, particularly effective in severe thyrotoxicosis.
## Footnote
This action occurs rapidly and can be crucial in emergency situations.
116
What happens to patients with hyperthyroidism when treated with iodide?
Release of thyroid hormone is rapidly blocked, and synthesis is mildly decreased.
## Footnote
Vascularity of the thyroid gland is reduced, and colloid reaccumulates in the follicles.
117
How long does it take for the maximal effect of iodide therapy in hyperthyroidism?
The maximal effect occurs after 10-15 days of continuous therapy.
## Footnote
This duration allows for significant changes in thyroid function.
118
What is the role of iodide therapy in the preoperative period for thyroidectomy?
Iodide therapy is used to prepare patients for thyroidectomy and in conjunction with antithyroid drugs and propranolol in thyrotoxic crisis.
## Footnote
This helps stabilize patients prior to surgery.
119
How does iodide protect the thyroid from radioactive iodine fallout?
Administration of stable iodine decreases the thyroid uptake of radioactive iodine.
## Footnote
This is crucial in the event of nuclear accidents.
120
What are the components of strong iodine solution (Lugol solution)?
5% iodine and 10% potassium iodide, yielding about 8 mg of iodine per drop.
## Footnote
This solution is commonly used in medical treatments.
121
What is the typical dosage for Lugol solution?
16-36 mg (2-6 drops) three times a day.
## Footnote
This dosage helps achieve the desired therapeutic effects.
122
What is the adult dose of potassium iodide product (Thyroshield) for radiation emergencies?
2 mL (130 mg) every 24 hours, as directed by public health officials.
## Footnote
This dosage is critical for blocking radioiodine uptake.
123
What condition may develop in euthyroid patients exposed to large amounts of iodine?
Iodine-induced hypothyroidism.
## Footnote
This can occur due to the acute Wolff-Chaikoff effect.
124
What are the prominent symptoms of sensitivity to iodine?
Angioedema and laryngeal edema may lead to suffocation.
## Footnote
Hypersensitivity reactions can be severe.
125
What symptoms are associated with chronic intoxication with iodide (iodism)?
Unpleasant brassy taste, burning in the mouth and throat, increased salivation, and irritation of the eyes.
## Footnote
These symptoms can resemble a cold.
126
What are potential severe reactions to prolonged use of iodides?
Rarely severe eruptions (ioderma) resembling those caused by bromism.
## Footnote
These eruptions can be serious and require withdrawal of iodide.
127
What gastrointestinal symptoms may occur with iodism?
Symptoms of gastric irritation, diarrhea (sometimes bloody), fever, anorexia, and depression.
## Footnote
These symptoms reflect the systemic effects of iodide.
128
What procedures can increase renal excretion of iodide?
Osmotic diuresis, chloruretic diuretics, and salt loading.
## Footnote
These methods can alleviate symptoms of iodism.
129
What is the iodine content of Amiodarone?
75 mg/200 mg tablet
## Footnote
Amiodarone is an antiarrhythmic medication that contains a significant amount of iodine.
130
What is the iodine content of Iodoquinol (diiodohydroxyquin)?
134 mg/tablet
## Footnote
Iodoquinol is used for treating intestinal infections and contains iodine.
131
What is the iodine content of Echothiophate iodide ophthalmic solution?
5-41 g/drop
## Footnote
This is an ophthalmic medication used in the treatment of glaucoma.
132
What is the iodine content of Iodoquinol?
134 mg/tablet
## Footnote
Iodoquinol is the same as diiodohydroxyquin, emphasizing its iodine content.
133
What is the iodine content of Idoxuridine ophthalmic solution?
18 ug/drop
## Footnote
Idoxuridine is an antiviral medication used to treat viral infections in the eye.
134
What is the iodine content of Lugol solution?
5-6 mg/drop
## Footnote
Lugol solution is a solution of iodine in water and is used as an antiseptic.
135
What is the iodine content of saturated solution of KI (KISS)?
38 mg/drop
## Footnote
KISS is used for various medical purposes including thyroid protection.
136
What is the iodine content of Clinoquinol cream?
Topical antiseptic
## Footnote
Clinoquinol is used topically and contains iodine.
137
What is the iodine content of Povidone-iodine?
Topical antiseptic
## Footnote
Povidone-iodine is a widely used antiseptic with iodine.
138
What is the iodine content of Diatrizoate meglumine sodium?
12 mg/g
## Footnote
This is a radiographic contrast agent used in imaging procedures.
139
What is the iodine content of lothalamate?
10 mg/mL
## Footnote
Lothalamate is another radiographic contrast agent with iodine.
140
What is the iodine content of loxaglate?
370 mg/mL
## Footnote
Loxaglate is used in radiographic imaging.
141
What is the iodine content of lopamidol?
320 mg/mL
## Footnote
Lopamidol is a contrast agent used in medical imaging.
142
What is the iodine content of Iohexol?
370 mg/mL
## Footnote
Iohexol is a non-ionic contrast agent used in various imaging studies.
143
What is the iodine content of Ioxilan?
350 mg/mL
## Footnote
Ioxilan is also a contrast agent used in imaging.
144
What is the iodine content of Iohexol?
370 mg/mL
## Footnote
Iohexol is frequently used in CT and other imaging studies.
145
What is the iodine content of Amiodarone?
75 mg/200 mg tablet
## Footnote
Amiodarone is an antiarrhythmic medication that contains a significant amount of iodine.
146
What is the iodine content of Iodoquinol (diiodohydroxyquin)?
134 mg/tablet
## Footnote
Iodoquinol is used for treating intestinal infections and contains iodine.
147
What is the iodine content of Echothiophate iodide ophthalmic solution?
5-41 g/drop
## Footnote
This is an ophthalmic medication used in the treatment of glaucoma.
148
What is the iodine content of Iodoquinol?
134 mg/tablet
## Footnote
Iodoquinol is the same as diiodohydroxyquin, emphasizing its iodine content.
149
What is the iodine content of Idoxuridine ophthalmic solution?
18 ug/drop
## Footnote
Idoxuridine is an antiviral medication used to treat viral infections in the eye.
150
What is the iodine content of Lugol solution?
5-6 mg/drop
## Footnote
Lugol solution is a solution of iodine in water and is used as an antiseptic.
151
What is the iodine content of saturated solution of KI (KISS)?
38 mg/drop
## Footnote
KISS is used for various medical purposes including thyroid protection.
152
What is the iodine content of Clinoquinol cream?
Topical antiseptic
## Footnote
Clinoquinol is used topically and contains iodine.
153
What is the iodine content of Povidone-iodine?
Topical antiseptic
## Footnote
Povidone-iodine is a widely used antiseptic with iodine.
154
What is the iodine content of Diatrizoate meglumine sodium?
12 mg/g
## Footnote
This is a radiographic contrast agent used in imaging procedures.
155
What is the iodine content of lothalamate?
10 mg/mL
## Footnote
Lothalamate is another radiographic contrast agent with iodine.
156
What is the iodine content of loxaglate?
370 mg/mL
## Footnote
Loxaglate is used in radiographic imaging.
157
What is the iodine content of lopamidol?
320 mg/mL
## Footnote
Lopamidol is a contrast agent used in medical imaging.
158
What is the iodine content of Iohexol?
370 mg/mL
## Footnote
Iohexol is a non-ionic contrast agent used in various imaging studies.
159
What is the iodine content of Ioxilan?
350 mg/mL
## Footnote
Ioxilan is also a contrast agent used in imaging.
160
What is the iodine content of Iohexol?
370 mg/mL
## Footnote
Iohexol is frequently used in CT and other imaging studies.
161
What are the primary isotopes used for the diagnosis and treatment of thyroid disease?
123I and 131I
## Footnote
123I is primarily used in diagnostic studies, while 131I is used therapeutically.
162
What is the half-life of 123I?
13 hours
163
What type of radiation does 131I emit?
Y rays and ß particles
164
What is the half-life of 131I?
8 days
165
What is the primary therapeutic use of 131I?
Thyroid destruction of an overactive or enlarged thyroid and thyroid ablation in cancer
166
How does the chemical behavior of radioactive isotopes of iodine compare to stable iodine?
Identical to that of stable isotope 127I
167
Where is 131I rapidly and efficiently trapped in the body?
Thyroid gland
168
What is the effect of 131I on surrounding tissue?
Little or no damage
169
True or False: The effects of radiation depend on the dosage.
True
170
What is the usual total dose of 131I for treatment?
4-15 mCi
171
What should be monitored alongside TSH concentrations after 131I therapy?
Free T4 and serum T3 concentrations
172
What is the recommended target dose of 131I to deliver to the thyroid gland?
8 mCi based on 24-h radioiodine uptake
173
Fill in the blank: Radioactive iodine is effective in patients with _______.
toxic nodular goiter
174
What are the advantages of radioactive iodine treatment?
Low cost, no hospitalization required, minimal discomfort
## Footnote
Patients can continue their usual activities during treatment.
175
What is a significant disadvantage of radioactive iodine treatment?
High incidence of delayed hypothyroidism
176
What types of cancer may show a small increase after radioiodine therapy?
Stomach, kidney, and breast cancers
177
What is the main contraindication for using 131I therapy?
Pregnancy
178
What is the purpose of withdrawing thyroid hormone replacement therapy before administering 131I?
To promote endogenous TSH stimulation for effective treatment
179
What is the range of an ablative dose of 131I for treating metastases?
30 to 150 mCi
180
What can be used instead of thyroid hormone withdrawal to prepare a patient for radioiodine ablation?
Recombinant thyrotropin alpha (recombinant human TSH)
181
True or False: Recombinant human TSH is currently approved for use in preparing patients for radioiodine ablation of metastatic disease.
False
182
What are the two primary histological classifications of thyroid carcinomas?
Papillary and follicular carcinomas
183
What is the primary treatment approach for most thyroid carcinomas?
Surgery, radioiodine, and levothyroxine to suppress TSH
184
What can be used to treat thyroid carcinomas that progress despite standard therapies?
Oral tyrosine kinase inhibitors sorafenib or lenvatinib
185
Is the response to sorafenib and lenvatinib dependent on specific oncogene mutations?
No
186
What is the recommended daily dose of sorafenib?
400 mg twice daily without food
187
List some adverse reactions associated with sorafenib
* Palmar-plantar erythrodysesthesia
* Diarrhea
* Alopecia
* Fatigue
* Weight loss
* Hypertension
* Others
188
What is the recommended daily dose of lenvatinib?
24 mg once daily with or without food
189
What should the lenvatinib dose be reduced to in patients with severe renal or hepatic impairment?
14 mg
190
List some adverse reactions associated with lenvatinib
* Hypertension
* Diarrhea
* Fatigue
* Decreased appetite
* Decreased weight
* Nausea
* Stomatitis
* Musculoskeletal pain
* Others
191
What type of thyroid cancer originates from parafollicular cells?
Medullary thyroid carcinomas
192
Are medullary thyroid carcinomas responsive to radioiodine or TSH suppression?
No
193
What can be used to treat medullary thyroid carcinomas that progress despite surgery?
Oral tyrosine kinase inhibitors vandetanib and cabozantinib
194
Can vandetanib and cabozantinib be prescribed regardless of RET gene mutational status?
Yes
195
What mutation was suggested to have a higher response rate in the phase III vandetanib trial?
RET M918T mutation
196
What did the phase III cabozantinib trial demonstrate regarding progression-free survival?
Longer progression-free survival in patients with RET M918T tumors and possibly RAS mutations
197
What is the recommended dose for vandetanib?
300 mg once daily with or without food
198
What is the reduced dose of vandetanib in moderate-to-severe renal impairment?
200 mg
199
What black-box warning is associated with vandetanib?
QT prolongation
200
List some adverse reactions associated with vandetanib
* Diarrhea
* Rash
* Nausea
* Hypertension
* Headache
* Others
201
What is the typical starting dose for cabozantinib?
60 to 100 mg on an empty stomach
202
What are the black-box warnings for cabozantinib?
* GI perforations and fistulas
* Hemorrhage
203
List some adverse reactions associated with cabozantinib
* Diarrhea
* Palmar-plantar erythrodysesthesia
* Decreased weight and appetite
* Nausea
* Fatigue
* Stomatitis
204
When should treatment with tyrosine kinase inhibitors continue?
Until the patient is no longer clinically benefiting or until unacceptable toxicity occurs
205
What should be monitored carefully in patients taking protein tyrosine kinase inhibitors?
TSH levels
206
Fill in the blank: Resistance to one tyrosine kinase inhibitor does not necessarily imply resistance to _______.
[another]
207
What can dosage reductions achieve in the treatment of thyroid cancer?
Mitigate toxicity
