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Questions and Answers
What is the impact of maternal hypothyroidism during the first trimester of pregnancy?
What is the impact of maternal hypothyroidism during the first trimester of pregnancy?
- It has no significant effects until after birth.
- It causes temporary weight gain in the mother.
- It can result in permanent neuropsychological deficits in the child. (correct)
- It leads to increased energy levels in the mother.
When should the dosage of thyroid supplements be increased for pregnant women taking levothyroxine?
When should the dosage of thyroid supplements be increased for pregnant women taking levothyroxine?
- Immediately after discovering the pregnancy.
- Only during labor.
- Between four and eight weeks after conception. (correct)
- At the end of the first trimester.
What is the primary action of levothyroxine (T4) in patients with hypothyroidism?
What is the primary action of levothyroxine (T4) in patients with hypothyroidism?
- It increases metabolism without any side effects.
- It reduces the absorption of other vitamins.
- It replaces thyroid hormones in the body. (correct)
- It cures the underlying cause of hypothyroidism.
How should levothyroxine be taken to ensure adequate absorption?
How should levothyroxine be taken to ensure adequate absorption?
What can result from an acute overdose of levothyroxine?
What can result from an acute overdose of levothyroxine?
Which of the following substances can reduce the absorption of levothyroxine?
Which of the following substances can reduce the absorption of levothyroxine?
What is the likely effect of drugs that accelerate the metabolism of levothyroxine?
What is the likely effect of drugs that accelerate the metabolism of levothyroxine?
Which statement is true regarding the half-life of levothyroxine?
Which statement is true regarding the half-life of levothyroxine?
What is the primary reason for reducing the dose of warfarin when a patient’s thyroid hormone levels increase?
What is the primary reason for reducing the dose of warfarin when a patient’s thyroid hormone levels increase?
What is true regarding the evaluation of levothyroxine therapy?
What is true regarding the evaluation of levothyroxine therapy?
Which patient population should avoid using methimazole during the first trimester of pregnancy?
Which patient population should avoid using methimazole during the first trimester of pregnancy?
What might happen if a patient with hyperthyroidism is treated with high doses of methimazole?
What might happen if a patient with hyperthyroidism is treated with high doses of methimazole?
How should levothyroxine be administered for optimal absorption?
How should levothyroxine be administered for optimal absorption?
What is a significant risk associated with the use of radioactive iodine treatment?
What is a significant risk associated with the use of radioactive iodine treatment?
Which statement about the use of antithyroid drugs in children is correct?
Which statement about the use of antithyroid drugs in children is correct?
What should a patient taking methimazole be instructed to watch for as signs of agranulocytosis?
What should a patient taking methimazole be instructed to watch for as signs of agranulocytosis?
When could levothyroxine dosages potentially need to be increased?
When could levothyroxine dosages potentially need to be increased?
Why is tight control of plasma levels important for levothyroxine?
Why is tight control of plasma levels important for levothyroxine?
Which factor is NOT a consideration when prescribing radioactive iodine?
Which factor is NOT a consideration when prescribing radioactive iodine?
For which condition is methimazole NOT indicated?
For which condition is methimazole NOT indicated?
What precaution is necessary when switching brands of levothyroxine?
What precaution is necessary when switching brands of levothyroxine?
What are the potential effects of maternal hypothyroidism on the child during pregnancy?
What are the potential effects of maternal hypothyroidism on the child during pregnancy?
Why is it important to take levothyroxine on an empty stomach?
Why is it important to take levothyroxine on an empty stomach?
What is a common sign of thyrotoxicosis following an acute overdose of levothyroxine?
What is a common sign of thyrotoxicosis following an acute overdose of levothyroxine?
What is the duration needed for plasma levels of thyroxine to reach a plateau after starting levothyroxine treatment?
What is the duration needed for plasma levels of thyroxine to reach a plateau after starting levothyroxine treatment?
Which of the following drugs can reduce the absorption of levothyroxine?
Which of the following drugs can reduce the absorption of levothyroxine?
What alteration should be expected in patients taking phenytoin while on levothyroxine?
What alteration should be expected in patients taking phenytoin while on levothyroxine?
What is a critical timeframe for increasing thyroid supplements in pregnant women already taking levothyroxine?
What is a critical timeframe for increasing thyroid supplements in pregnant women already taking levothyroxine?
What possible effect does levothyroxine have on warfarin therapy?
What possible effect does levothyroxine have on warfarin therapy?
What is one potential adverse effect of taking high doses of methimazole?
What is one potential adverse effect of taking high doses of methimazole?
Which of the following statements is true regarding the use of radioactive iodine?
Which of the following statements is true regarding the use of radioactive iodine?
How long after starting levothyroxine therapy should evaluation be conducted?
How long after starting levothyroxine therapy should evaluation be conducted?
What factor must be considered when changing levothyroxine brands?
What factor must be considered when changing levothyroxine brands?
Which group of patients should specifically avoid the use of methimazole?
Which group of patients should specifically avoid the use of methimazole?
What is the primary use of PTU in pregnancy?
What is the primary use of PTU in pregnancy?
What symptom should patients watch for as an indication of agranulocytosis while on methimazole?
What symptom should patients watch for as an indication of agranulocytosis while on methimazole?
Which therapeutic effect of levothyroxine warrants the need for tight control of plasma drug levels?
Which therapeutic effect of levothyroxine warrants the need for tight control of plasma drug levels?
What is a contraindication for using radioactive iodine in treating hyperthyroidism?
What is a contraindication for using radioactive iodine in treating hyperthyroidism?
What treatment is often recommended for infants with hypothyroidism?
What treatment is often recommended for infants with hypothyroidism?
For which condition is methimazole NOT used?
For which condition is methimazole NOT used?
What is a potential risk of using antithyroid drugs in the older adult population?
What is a potential risk of using antithyroid drugs in the older adult population?
When converting from hypothyroid to euthyroid states, which medications may need increased dosages?
When converting from hypothyroid to euthyroid states, which medications may need increased dosages?
Which of the following is a key factor for prescribers to consider in patient-centered care for thyroid medications across different age groups?
Which of the following is a key factor for prescribers to consider in patient-centered care for thyroid medications across different age groups?
Flashcards
Maternal Hypothyroidism & Pregnancy
Maternal Hypothyroidism & Pregnancy
Untreated maternal hypothyroidism during pregnancy can cause lasting intellectual problems in the child, primarily in the first trimester.
Fetal Thyroid Function
Fetal Thyroid Function
By the second trimester, the fetus's thyroid gland is fully functional, allowing for independent hormone production.
Levothyroxine (T4)
Levothyroxine (T4)
Synthetic thyroid hormone, the first-line treatment for hypothyroidism, converted to T3.
Levothyroxine Administration
Levothyroxine Administration
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Levothyroxine & Food
Levothyroxine & Food
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Levothyroxine Interactions (Decreased Absorption)
Levothyroxine Interactions (Decreased Absorption)
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Levothyroxine Interactions (Increased Metabolism)
Levothyroxine Interactions (Increased Metabolism)
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Levothyroxine Overdose Symptoms
Levothyroxine Overdose Symptoms
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Warfarin dose reduction
Warfarin dose reduction
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Levothyroxine and Insulin/Digoxin
Levothyroxine and Insulin/Digoxin
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Levothyroxine's therapeutic range
Levothyroxine's therapeutic range
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Bioequivalent Medications
Bioequivalent Medications
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Methimazole (First-line drug)
Methimazole (First-line drug)
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Methimazole Pregnancy/Lactation
Methimazole Pregnancy/Lactation
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Methimazole Agranulocytosis
Methimazole Agranulocytosis
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Radioactive Iodine
Radioactive Iodine
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Radioactive Iodine Pregnancy/Lactation
Radioactive Iodine Pregnancy/Lactation
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TSH Evaluation in Hypothyroidism
TSH Evaluation in Hypothyroidism
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Hypothyroidism Treatment Duration
Hypothyroidism Treatment Duration
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Infant Hypothyroidism Treatment
Infant Hypothyroidism Treatment
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Older Adult Thyroid Dysfunction
Older Adult Thyroid Dysfunction
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PTU vs Methimazole
PTU vs Methimazole
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Maternal Hypothyroidism Impact
Maternal Hypothyroidism Impact
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Fetal Thyroid Development
Fetal Thyroid Development
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Levothyroxine (T4) - The Key
Levothyroxine (T4) - The Key
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Levothyroxine Timing
Levothyroxine Timing
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Levothyroxine & Food Troubles
Levothyroxine & Food Troubles
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Levothyroxine Interactions
Levothyroxine Interactions
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Levothyroxine Overdose
Levothyroxine Overdose
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Warfarin & Levothyroxine
Warfarin & Levothyroxine
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Levothyroxine Dose Adjustment
Levothyroxine Dose Adjustment
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Levothyroxine Bioequivalence
Levothyroxine Bioequivalence
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Methimazole: First-Line for Hyperthyroidism
Methimazole: First-Line for Hyperthyroidism
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Methimazole Pregnancy Precautions?
Methimazole Pregnancy Precautions?
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Methimazole Agranulocytosis: A Serious Risk
Methimazole Agranulocytosis: A Serious Risk
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Radioactive Iodine: A Hyperthyroidism Treatment
Radioactive Iodine: A Hyperthyroidism Treatment
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Evaluating Hypothyroidism Therapy
Evaluating Hypothyroidism Therapy
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Thyroid Dysfunction in Older Adults
Thyroid Dysfunction in Older Adults
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PTU: A Safer Option in Early Pregnancy
PTU: A Safer Option in Early Pregnancy
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Warfarin Dose Adjustment: A Thyroid Link
Warfarin Dose Adjustment: A Thyroid Link
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Study Notes
Hypothyroidism and Pregnancy
- Maternal hypothyroidism during the first trimester can cause permanent neuropsychological issues in the child.
- Fetal thyroid function fully develops by the second trimester, enabling the fetus to produce its own hormones.
- Early diagnosis and treatment of hypothyroidism are crucial.
- Pregnant women taking thyroid supplements require a dosage increase, often by 50%, starting between four and eight weeks.
Thyroid Hormone Preparations for Hypothyroidism (Levothyroxine)
- Levothyroxine (T4), a synthetic thyroxine, is the preferred drug for most hypothyroidism cases.
- Take levothyroxine on an empty stomach, 30-60 minutes before breakfast, as food reduces absorption.
- Most levothyroxine is converted to T3 in the body.
- It has a prolonged half-life (approximately one month for plasma levels to reach plateau) and is highly protein-bound.
- Safe for all types of hypothyroidism.
- Adverse effects are rare. Acute overdose can lead to thyrotoxicosis (symptoms include tachycardia, angina, tremor, nervousness, insomnia, hyperthermia, heat intolerance, and sweating).
- Drugs that reduce levothyroxine absorption include H2 blockers, proton pump inhibitors, sucralfate, cholestyramine, colestipol, aluminum-containing antacids, calcium supplements, iron supplements, magnesium salts, and orlistat. Spacing administration by 4 hours is crucial.
- Drugs that accelerate levothyroxine metabolism include phenytoin, carbamazepine, rifampin, sertraline, and phenobarbital. Patients taking these drugs might need increased levothyroxine doses.
- Warfarin doses may need adjustment as levothyroxine speeds up vitamin K-dependent clotting factor breakdown.
- Catecholamines' effect may increase due to thyroid hormones' impact on cardiac responsiveness.
- Levothyroxine can increase insulin and digoxin needs. Dosages of these drugs might need adjustment when treating a hypothyroid patient to an euthyroid state.
- Levothyroxine has a narrow therapeutic index. Precise control of plasma levels is essential.
- Bioequivalent products are critical when switching brands, and the prescriber should be notified of any changes.
- Almost always administered orally, once daily on an empty stomach. IV administration might be used in myxedema coma.
- Evaluation: A combination of clinical judgment and lab tests (serum TSH) is used to determine dosage. Elevated TSH levels declining indicate successful treatment. TSH normalization is gradual, and evaluation should occur 6-8 weeks after initiating treatment.
- Occasionally Serum T4 is used for evaluation as TSH may remain elevated despite restored thyroid hormone levels..
- Replacement therapy is typically lifelong; resolution of symptoms does not mean cessation.
Drugs for Hyperthyroidism (Methimazole)
- Methimazole (first-line) inhibits thyroid hormone synthesis.
- Not used during first trimester of pregnancy, but can be used in the second/third trimester.
- Therapy may take 3 to 12 weeks for treatment to be fully effective.
- Well absorbed orally, crosses membranes (including placenta and breast milk).
- Relatively long half-life (6-13 hours), allowing once-daily dosing. Effective in Graves' disease, radiation therapy support, surgical prep, and thyrotoxic crisis.
- Adverse effects include:
- Agranulocytosis (most dangerous toxicity; sore throat, fever; early indications; immediate reporting).
- Hypothyroidism (high dosage).
- Effects in pregnancy:
- Neonatal hypothyroidism, goiter, and congenital hypothyroidism are possible, particularly in first trimester.
- PTU is preferred over methimazole in first-trimester pregnancy due to its lower placental crossing potential.
- Effects on breastfeeding are minimal, up to 20 mg daily isn't problematic.
Radioactive Iodine
- Specialist-prescribed for destroying thyroid tissue (Graves' disease).
- Relatively low cost, avoids surgery.
- Effective treatment, but delayed (several months for max effect).
- Risks include delayed hypothyroidism.
- Contraindicated in pregnancy and lactation.
- Dosage determined by thyroid size and iodine uptake.
Patient-Centered Care Across the Lifespan
- Infants: Hypothyroidism treatment; three-year regimen.
- Children/Adolescents: Thyroid hormone and Antithyroid drugs. Iodine not typical. Dosing individualized.
- Pregnant women: Iodine-131 contraindicated; first-trimester Methimazole avoidance.
- Breastfeeding women: Thyroid hormone and antithyroid medications generally safe.
- Older adults: Thyroid dysfunction is prevalent, requiring timely treatment with hormone and antithyroid medications for better health outcomes.
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