Podcast
Questions and Answers
What is the recommended time window for administering levothyroxine in relation to meals?
What is the recommended time window for administering levothyroxine in relation to meals?
- 60 minutes before meals or 4 hours after meals (correct)
- 30 minutes before meals or 2 hours after meals
- 45 minutes before meals or 3 hours after meals
- 90 minutes before meals or 6 hours after meals
Why should levothyroxine dosage changes be made slowly?
Why should levothyroxine dosage changes be made slowly?
- To prevent allergic reactions
- To reduce the risk of overdose
- To minimize the risk of drug interactions
- To avoid transient serum alterations (correct)
What is the half-life of levothyroxine?
What is the half-life of levothyroxine?
- 7 days (correct)
- 24 hours
- 48 hours
- 12 hours
Why is liotyronine (T3) not recommended for long-term use?
Why is liotyronine (T3) not recommended for long-term use?
What is the clinical indication for levothyroxine administration?
What is the clinical indication for levothyroxine administration?
What is the most appropriate initial levothyroxine replacement dose for a young patient with no cardiac disease?
What is the most appropriate initial levothyroxine replacement dose for a young patient with no cardiac disease?
Why should levothyroxine be taken orally on an empty stomach or at bedtime?
Why should levothyroxine be taken orally on an empty stomach or at bedtime?
When should thyroid function tests be monitored after starting levothyroxine therapy?
When should thyroid function tests be monitored after starting levothyroxine therapy?
Why might lower thyroxine doses be considered for a patient taking omeprazole?
Why might lower thyroxine doses be considered for a patient taking omeprazole?
When should levothyroxine administration be separated from calcium intake?
When should levothyroxine administration be separated from calcium intake?
What is the primary reason for the initial methimazole treatment being preferred over propylthiouracil?
What is the primary reason for the initial methimazole treatment being preferred over propylthiouracil?
What is the rationale for preferring once daily dosing of methimazole over propylthiouracil?
What is the rationale for preferring once daily dosing of methimazole over propylthiouracil?
What is the recommended administration frequency for methimazole?
What is the recommended administration frequency for methimazole?
Why was methimazole preferred over propylthiouracil for initial treatment?
Why was methimazole preferred over propylthiouracil for initial treatment?
What is the role of serum FT4 and FT3 concentrations in determining the hormone's biological activity?
What is the role of serum FT4 and FT3 concentrations in determining the hormone's biological activity?
What is the primary mechanism by which T4 is converted to T3?
What is the primary mechanism by which T4 is converted to T3?
What is the preferable practice for patients using levothyroxine to avoid changes in bioavailability?
What is the preferable practice for patients using levothyroxine to avoid changes in bioavailability?
Which type of thyroxine is the preparation of choice for thyroid replacement and suppression therapy?
Which type of thyroxine is the preparation of choice for thyroid replacement and suppression therapy?
Which component is responsible for the stability and content uniformity of levothyroxine preparations?
Which component is responsible for the stability and content uniformity of levothyroxine preparations?
What is the effect of iodide therapy on the size and vascularity of a hyperplastic thyroid gland?
What is the effect of iodide therapy on the size and vascularity of a hyperplastic thyroid gland?
When is iodide therapy clinically indicated for thyroid storm?
When is iodide therapy clinically indicated for thyroid storm?
Why should chronic use of iodides in pregnancy be avoided?
Why should chronic use of iodides in pregnancy be avoided?
What are the disadvantages of iodide therapy?
What are the disadvantages of iodide therapy?
What are the toxicities associated with chronic use of iodides?
What are the toxicities associated with chronic use of iodides?
Which antithyroid medication is preferably given in the 1st trimester of pregnancy due to its strong protein binding and reduced placental crossing?
Which antithyroid medication is preferably given in the 1st trimester of pregnancy due to its strong protein binding and reduced placental crossing?
What is the primary pharmacodynamic action of thioamides like Methimazole and Propylthiouracil?
What is the primary pharmacodynamic action of thioamides like Methimazole and Propylthiouracil?
Which antithyroid medication inhibits peripheral deiodination of T4 to T3?
Which antithyroid medication inhibits peripheral deiodination of T4 to T3?
What is the most dangerous adverse reaction associated with thioamides like Methimazole and Propylthiouracil?
What is the most dangerous adverse reaction associated with thioamides like Methimazole and Propylthiouracil?
Why are iodides rarely used as sole therapy for hyperthyroidism today?
Why are iodides rarely used as sole therapy for hyperthyroidism today?
What effect do thioamides have on hormone synthesis?
What effect do thioamides have on hormone synthesis?
What distinguishes the onset of thioamides from other antithyroid agents?
What distinguishes the onset of thioamides from other antithyroid agents?
What is the reported incidence of severe hepatitis associated with Propylthiouracil (PTU) use?
What is the reported incidence of severe hepatitis associated with Propylthiouracil (PTU) use?
Which antithyroid medication is associated with a higher incidence of cholestatic jaundice?
Which antithyroid medication is associated with a higher incidence of cholestatic jaundice?
What percentage of patients experience agranulocytosis due to thioamide treatment?
What percentage of patients experience agranulocytosis due to thioamide treatment?
Which of the following is a characteristic symptom of hyperthyroidism?
Which of the following is a characteristic symptom of hyperthyroidism?
Which antithyroid drug has a half-life of about 1.5 hours?
Which antithyroid drug has a half-life of about 1.5 hours?
Which of the following drugs is an active metabolite of Carbimazole?
Which of the following drugs is an active metabolite of Carbimazole?
What is the primary pharmacological action of Propylthiouracil?
What is the primary pharmacological action of Propylthiouracil?
What is the preferable and effective strategy for definitive treatment of hyperthyroidism before becoming pregnant?
What is the preferable and effective strategy for definitive treatment of hyperthyroidism before becoming pregnant?
What is the effect of radioactive iodine (RAI) therapy on JP's thyroid function?
What is the effect of radioactive iodine (RAI) therapy on JP's thyroid function?
Why did JP receive calcium carbonate three times daily?
Why did JP receive calcium carbonate three times daily?
What is the significance of JP's delayed reflexes on physical examination?
What is the significance of JP's delayed reflexes on physical examination?
What is the primary reason for JP's weight gain despite experiencing symptoms of hyperthyroidism previously?
What is the primary reason for JP's weight gain despite experiencing symptoms of hyperthyroidism previously?
Why did JP receive omeprazole?
Why did JP receive omeprazole?
What is the primary cause of primary hypothyroidism?
What is the primary cause of primary hypothyroidism?
Which medication is part of the treatment protocol for differentiated thyroid cancer to prevent recurrence after total thyroidectomy?
Which medication is part of the treatment protocol for differentiated thyroid cancer to prevent recurrence after total thyroidectomy?
What is the primary mechanism of action of anti-thyroid hormones like Methimazole and Carbimazole?
What is the primary mechanism of action of anti-thyroid hormones like Methimazole and Carbimazole?
What is the primary cause of secondary or central hypothyroidism?
What is the primary cause of secondary or central hypothyroidism?
Which type of antithyroid medication reduces thyroid activity and hormone effects by interfering with the production of thyroid hormones?
Which type of antithyroid medication reduces thyroid activity and hormone effects by interfering with the production of thyroid hormones?
Which drug is indicated for the preoperative preparation of a hyperplastic thyroid gland to decrease size and vascularity?
Which drug is indicated for the preoperative preparation of a hyperplastic thyroid gland to decrease size and vascularity?
What is the primary disadvantage of iodide therapy?
What is the primary disadvantage of iodide therapy?
What is a potential adverse reaction associated with chronic use of iodides?
What is a potential adverse reaction associated with chronic use of iodides?
In which clinical condition is iodide therapy contraindicated?
In which clinical condition is iodide therapy contraindicated?
What effect does iodide therapy have on a hyperplastic thyroid gland?
What effect does iodide therapy have on a hyperplastic thyroid gland?
How is radioactive iodine administered for the treatment of thyrotoxicosis?
How is radioactive iodine administered for the treatment of thyrotoxicosis?
What is the effective half-life of the β rays emitted by radioactive iodine for the treatment of thyrotoxicosis?
What is the effective half-life of the β rays emitted by radioactive iodine for the treatment of thyrotoxicosis?
What is a significant advantage of radioiodine therapy for hyperthyroidism?
What is a significant advantage of radioiodine therapy for hyperthyroidism?
Why should radioactive iodine not be administered to pregnant women or nursing mothers?
Why should radioactive iodine not be administered to pregnant women or nursing mothers?
What clinical syndrome results from tissues being exposed to high levels of thyroid hormone?
What clinical syndrome results from tissues being exposed to high levels of thyroid hormone?
What is the optimal TSH range that should be maintained for patients undergoing levothyroxine therapy?
What is the optimal TSH range that should be maintained for patients undergoing levothyroxine therapy?
What is the suggested time interval for separating levothyroxine administration from calcium intake to ensure optimal absorption?
What is the suggested time interval for separating levothyroxine administration from calcium intake to ensure optimal absorption?
What may be a reason for inadequate levothyroxine replacement in a patient with an elevated TSH level?
What may be a reason for inadequate levothyroxine replacement in a patient with an elevated TSH level?
What is the suggested approach to optimize levothyroxine absorption in a patient taking omeprazole?
What is the suggested approach to optimize levothyroxine absorption in a patient taking omeprazole?
When should thyroid function tests be monitored after starting levothyroxine therapy?
When should thyroid function tests be monitored after starting levothyroxine therapy?
What is the effect of chronic use of iodides in pregnancy?
What is the effect of chronic use of iodides in pregnancy?
For whom may once weekly thyroxine injections be effective?
For whom may once weekly thyroxine injections be effective?
Which antithyroid medication inhibits peripheral deiodination of T4 to T3?
Which antithyroid medication inhibits peripheral deiodination of T4 to T3?
Why might lower thyroxine doses also be considered for a patient taking omeprazole?
Why might lower thyroxine doses also be considered for a patient taking omeprazole?
What is the primary role of TSH Releasing Hormone (TRH) in regulating thyroid hormones?
What is the primary role of TSH Releasing Hormone (TRH) in regulating thyroid hormones?
What is the physiological consequence of low levels of T3 and T4 in the blood?
What is the physiological consequence of low levels of T3 and T4 in the blood?
What is the exclusive physiological role of iodine in relation to thyroid hormones?
What is the exclusive physiological role of iodine in relation to thyroid hormones?
Which organ plays a critical role in regulating metabolic activities such as body temperature and menstrual cycles?
Which organ plays a critical role in regulating metabolic activities such as body temperature and menstrual cycles?
What is the primary function of THYROXINE (T4) and TRIIODOTHYRONINE (T3) in the body?
What is the primary function of THYROXINE (T4) and TRIIODOTHYRONINE (T3) in the body?
What is the recommended time window for administering levothyroxine in relation to meals?
What is the recommended time window for administering levothyroxine in relation to meals?
Why is liotyronine (T3) not recommended for long-term use?
Why is liotyronine (T3) not recommended for long-term use?
What is the optimal TSH range that should be maintained for patients undergoing levothyroxine therapy?
What is the optimal TSH range that should be maintained for patients undergoing levothyroxine therapy?
What is the primary pharmacological action of Propylthiouracil?
What is the primary pharmacological action of Propylthiouracil?
What effect do certain foods and drugs have on the absorption of levothyroxine?
What effect do certain foods and drugs have on the absorption of levothyroxine?
What is the primary clinical indication for thyroid storm?
What is the primary clinical indication for thyroid storm?
Which of the following is a disadvantage of iodide therapy?
Which of the following is a disadvantage of iodide therapy?
What is the potential toxicity associated with chronic use of iodides in pregnancy?
What is the potential toxicity associated with chronic use of iodides in pregnancy?
What is the primary adverse reaction to iodine (IODISM)?
What is the primary adverse reaction to iodine (IODISM)?
Which clinical condition is iodide therapy contraindicated?
Which clinical condition is iodide therapy contraindicated?
What is the most significant advantage of levothyroxine over liothyronine for thyroid hormone replacement therapy?
What is the most significant advantage of levothyroxine over liothyronine for thyroid hormone replacement therapy?
In the context of thyroid hormone replacement therapy, which factor favors the use of liothyronine over levothyroxine?
In the context of thyroid hormone replacement therapy, which factor favors the use of liothyronine over levothyroxine?
In a patient with hypothyroidism, which symptom is most likely to persist despite adequate levothyroxine replacement?
In a patient with hypothyroidism, which symptom is most likely to persist despite adequate levothyroxine replacement?
Which characteristic best describes the action of thioamides like carbimazole and methimazole in the treatment of hyperthyroidism?
Which characteristic best describes the action of thioamides like carbimazole and methimazole in the treatment of hyperthyroidism?
In the treatment of neonatal Grave’s disease, which mechanism supports the use of antithyroid drugs like propylthiouracil and methimazole?
In the treatment of neonatal Grave’s disease, which mechanism supports the use of antithyroid drugs like propylthiouracil and methimazole?
What is the primary cause of primary hypothyroidism?
What is the primary cause of primary hypothyroidism?
In the context of thyroid hormone replacement therapy, what is the primary function of Thioamides?
In the context of thyroid hormone replacement therapy, what is the primary function of Thioamides?
What is the clinical significance of TSH suppression in the context of differentiated thyroid cancer treatment?
What is the clinical significance of TSH suppression in the context of differentiated thyroid cancer treatment?
What is the primary difference between primary hypothyroidism and secondary (central) hypothyroidism?
What is the primary difference between primary hypothyroidism and secondary (central) hypothyroidism?
What is the primary effect of Iodides in the context of anti-thyroid hormones?
What is the primary effect of Iodides in the context of anti-thyroid hormones?
What is the recommended approach to optimize levothyroxine absorption in a patient taking omeprazole?
What is the recommended approach to optimize levothyroxine absorption in a patient taking omeprazole?
Why might lower thyroxine doses be considered for a patient taking omeprazole?
Why might lower thyroxine doses be considered for a patient taking omeprazole?
What is the primary role of liothyronine in thyroid hormone replacement therapy?
What is the primary role of liothyronine in thyroid hormone replacement therapy?
When should thyroid function tests be monitored after starting levothyroxine therapy?
When should thyroid function tests be monitored after starting levothyroxine therapy?
Why might once weekly thyroxine injections be effective for some patients?
Why might once weekly thyroxine injections be effective for some patients?
What is the primary advantage of using synthetic levothyroxine for thyroid replacement and suppression therapy?
What is the primary advantage of using synthetic levothyroxine for thyroid replacement and suppression therapy?
In the context of thyroid hormone replacement, what differentiates levothyroxine from liothyronine?
In the context of thyroid hormone replacement, what differentiates levothyroxine from liothyronine?
What is the key consideration for maintaining patients on a consistent levothyroxine preparation between refills?
What is the key consideration for maintaining patients on a consistent levothyroxine preparation between refills?
In the context of thyroid function evaluation, which combination of hormone levels indicates hyperthyroidism?
In the context of thyroid function evaluation, which combination of hormone levels indicates hyperthyroidism?
What is the primary role of thyroxine-binding globulin (TBG) in the transport of thyroid hormones?
What is the primary role of thyroxine-binding globulin (TBG) in the transport of thyroid hormones?
What is the primary role of Thyroid-Stimulating Hormone (TSH) in regulating thyroid hormones?
What is the primary role of Thyroid-Stimulating Hormone (TSH) in regulating thyroid hormones?
What is the exclusive physiological role of iodine in relation to thyroid hormones?
What is the exclusive physiological role of iodine in relation to thyroid hormones?
What is the primary pharmacodynamic action of thioamides like Methimazole and Propylthiouracil?
What is the primary pharmacodynamic action of thioamides like Methimazole and Propylthiouracil?
What is the suggested approach to optimize levothyroxine absorption in a patient taking omeprazole?
What is the suggested approach to optimize levothyroxine absorption in a patient taking omeprazole?
What is the role of serum FT4 and FT3 concentrations in determining the hormone's biological activity?
What is the role of serum FT4 and FT3 concentrations in determining the hormone's biological activity?
Why is liotyronine (T3) not recommended for long-term use?
Why is liotyronine (T3) not recommended for long-term use?
How does iodide therapy affect the size and vascularity of a hyperplastic thyroid gland?
How does iodide therapy affect the size and vascularity of a hyperplastic thyroid gland?
Which adverse reaction is more commonly associated with methimazole compared to Propylthiouracil?
Which adverse reaction is more commonly associated with methimazole compared to Propylthiouracil?
What is the primary mechanism of action of Propylthiouracil in inhibiting hormone synthesis?
What is the primary mechanism of action of Propylthiouracil in inhibiting hormone synthesis?
What was the major antithyroid agent prior to the introduction of thioamides in the 1940s?
What was the major antithyroid agent prior to the introduction of thioamides in the 1940s?
What is the most dangerous complication associated with thioamides like Propylthiouracil and Methimazole?
What is the most dangerous complication associated with thioamides like Propylthiouracil and Methimazole?
What is the role of iodides in the context of anti-thyroid hormones?
What is the role of iodides in the context of anti-thyroid hormones?
What is the primary pharmacological action of Propylthiouracil and Methimazole?
What is the primary pharmacological action of Propylthiouracil and Methimazole?
What is the potential toxicity associated with chronic use of iodides in pregnancy?
What is the potential toxicity associated with chronic use of iodides in pregnancy?
Why are iodides rarely used as sole therapy for hyperthyroidism today?
Why are iodides rarely used as sole therapy for hyperthyroidism today?
How does radioactive iodine (RAI) therapy affect thyroid function?
How does radioactive iodine (RAI) therapy affect thyroid function?
What is the effect of iodide therapy on a hyperplastic thyroid gland?
What is the effect of iodide therapy on a hyperplastic thyroid gland?
Which of the following antithyroid medications has a longer duration of action allowing once daily dosing and an improved safety profile?
Which of the following antithyroid medications has a longer duration of action allowing once daily dosing and an improved safety profile?
What is the primary cause of secondary or central hypothyroidism?
What is the primary cause of secondary or central hypothyroidism?
What is the potential toxicity associated with chronic use of iodides in pregnancy?
What is the potential toxicity associated with chronic use of iodides in pregnancy?
In the context of thyroid function, what effect does iodide therapy have on the size and vascularity of a hyperplastic thyroid gland?
In the context of thyroid function, what effect does iodide therapy have on the size and vascularity of a hyperplastic thyroid gland?
What distinguishes the onset of thioamides like Methimazole from other antithyroid agents?
What distinguishes the onset of thioamides like Methimazole from other antithyroid agents?
Which medication has the primary pharmacodynamic action of inhibiting thyroid hormone synthesis by interfering with iodine oxidation and organification?
Which medication has the primary pharmacodynamic action of inhibiting thyroid hormone synthesis by interfering with iodine oxidation and organification?
In the context of toxicity, which medication is associated with a rare but serious adverse effect known as agranulocytosis, a significant reduction in white blood cells?
In the context of toxicity, which medication is associated with a rare but serious adverse effect known as agranulocytosis, a significant reduction in white blood cells?
What is the primary reason why radioactive iodine should not be administered to pregnant women or nursing mothers?
What is the primary reason why radioactive iodine should not be administered to pregnant women or nursing mothers?
In the context of hyperthyroidism, which medication is contraindicated due to its potential to worsen the condition by causing temporary hypothyroidism followed by a surge in thyroid hormone production?
In the context of hyperthyroidism, which medication is contraindicated due to its potential to worsen the condition by causing temporary hypothyroidism followed by a surge in thyroid hormone production?
Which medication is primarily used for the acute management of severe hyperthyroidism such as thyroid storm, due to its additional effect of inhibiting the peripheral conversion of T4 to T3?
Which medication is primarily used for the acute management of severe hyperthyroidism such as thyroid storm, due to its additional effect of inhibiting the peripheral conversion of T4 to T3?
What is the primary mechanism of action of Thioamides like Methimazole and Carbimazole?
What is the primary mechanism of action of Thioamides like Methimazole and Carbimazole?
What is the most significant adverse effect associated with the chronic use of Iodides for hyperthyroidism?
What is the most significant adverse effect associated with the chronic use of Iodides for hyperthyroidism?
What is the primary pharmacodynamic action of Propylthiouracil (PTU)?
What is the primary pharmacodynamic action of Propylthiouracil (PTU)?
What is the effect of radioactive iodine (RAI) therapy on a hyperplastic thyroid gland?
What is the effect of radioactive iodine (RAI) therapy on a hyperplastic thyroid gland?
In the context of iodide therapy, what is the most common toxicity associated with chronic use?
In the context of iodide therapy, what is the most common toxicity associated with chronic use?
What is the primary advantage of methimazole over propylthiouracil in the treatment of hyperthyroidism?
What is the primary advantage of methimazole over propylthiouracil in the treatment of hyperthyroidism?
In the context of iodide therapy for hyperthyroidism, what is the most significant disadvantage of using iodides?
In the context of iodide therapy for hyperthyroidism, what is the most significant disadvantage of using iodides?
Why is iodide therapy contraindicated in patients with multinodular goiter?
Why is iodide therapy contraindicated in patients with multinodular goiter?
What is the primary pharmacological action of radioactive iodine in the treatment of hyperthyroidism?
What is the primary pharmacological action of radioactive iodine in the treatment of hyperthyroidism?
Why is methimazole preferred over propylthiouracil for initial treatment in pregnant patients with hyperthyroidism?
Why is methimazole preferred over propylthiouracil for initial treatment in pregnant patients with hyperthyroidism?
What is the primary pharmacological action of Propylthiouracil?
What is the primary pharmacological action of Propylthiouracil?
What is the potential toxicity associated with chronic use of iodides in pregnancy?
What is the potential toxicity associated with chronic use of iodides in pregnancy?
What is the primary cause of primary hypothyroidism?
What is the primary cause of primary hypothyroidism?
What is the primary effect of Iodides in the context of anti-thyroid hormones?
What is the primary effect of Iodides in the context of anti-thyroid hormones?
When is iodide therapy clinically indicated for thyroid storm?
When is iodide therapy clinically indicated for thyroid storm?
What is the reported incidence of severe hepatitis associated with Propylthiouracil (PTU) use?
What is the reported incidence of severe hepatitis associated with Propylthiouracil (PTU) use?
What is the potential adverse reaction associated with chronic use of iodides?
What is the potential adverse reaction associated with chronic use of iodides?
What is the primary role of Thyroid-Stimulating Hormone (TSH) in regulating thyroid hormones?
What is the primary role of Thyroid-Stimulating Hormone (TSH) in regulating thyroid hormones?
What is the exclusive physiological role of iodine in relation to thyroid hormones?
What is the exclusive physiological role of iodine in relation to thyroid hormones?
What is the primary difference between primary hypothyroidism and secondary (central) hypothyroidism?
What is the primary difference between primary hypothyroidism and secondary (central) hypothyroidism?
Flashcards
Levothyroxine Administration
Levothyroxine Administration
Administer levothyroxine on an empty stomach or at bedtime for optimal absorption.
Levothyroxine Dosage Changes
Levothyroxine Dosage Changes
Slowly adjust levothyroxine dosage to prevent adverse effects and allow body adjustment.
Levothyroxine Half-Life
Levothyroxine Half-Life
Approximately 7 days, leading to once-daily dosing.
Initial Levothyroxine Dose (Young, No Cardiac Disease)
Initial Levothyroxine Dose (Young, No Cardiac Disease)
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Monitoring Thyroid Function Tests (TFTs)
Monitoring Thyroid Function Tests (TFTs)
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Levothyroxine Clinical Indications
Levothyroxine Clinical Indications
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Liothyronine (T3) Use
Liothyronine (T3) Use
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Levothyroxine and Calcium
Levothyroxine and Calcium
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Methimazole vs. PTU
Methimazole vs. PTU
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PTU Mechanism
PTU Mechanism
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Iodide Therapy Indication
Iodide Therapy Indication
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Iodide Therapy in Pregnancy
Iodide Therapy in Pregnancy
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Iodide Therapy Contraindications
Iodide Therapy Contraindications
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PTU Adverse Reaction
PTU Adverse Reaction
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Thioamide (Methimazole/PTU) Adverse Effect
Thioamide (Methimazole/PTU) Adverse Effect
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Iodism Symptoms
Iodism Symptoms
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Chronic Iodide Therapy
Chronic Iodide Therapy
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Radioactive Iodine Therapy Use
Radioactive Iodine Therapy Use
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Radioactive Iodine Therapy Admin
Radioactive Iodine Therapy Admin
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Primary Hypothyroidism Cause
Primary Hypothyroidism Cause
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TSH Releasing Hormone (TRH)
TSH Releasing Hormone (TRH)
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T4 and T3 Function
T4 and T3 Function
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Thyroxine Monitoring (e.g. with omeprazole)
Thyroxine Monitoring (e.g. with omeprazole)
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Thyroxine Injection Frequency
Thyroxine Injection Frequency
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Optimal TSH Range (Levothyroxine)
Optimal TSH Range (Levothyroxine)
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Hyperthyroidism Symptoms
Hyperthyroidism Symptoms
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Low Levothyroxine Replacement
Low Levothyroxine Replacement
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Study Notes
Levothyroxine Administration and Monitoring
- Levothyroxine should be administered on an empty stomach or at bedtime to enhance absorption.
- Dosage changes for levothyroxine should be made slowly to prevent adverse effects and allow the body to adjust.
- The half-life of levothyroxine is approximately 7 days, allowing for once-daily dosing.
- Initial levothyroxine replacement dose recommended for young patients without cardiac disease is typically 1.6 to 1.8 mcg/kg/day.
- Thyroid function tests should be monitored 6-8 weeks after starting levothyroxine therapy.
Clinical Indications and Specifics
- Clinical indication for levothyroxine administration includes hypothyroidism and post-thyroidectomy for cancer.
- Liothyronine (T3) is not recommended for long-term use due to its shorter half-life and potential fluctuation in hormone levels.
- Levothyroxine absorption may be affected by calcium intake; separation from calcium supplements is advised.
Antithyroid Medications
- Methimazole is preferred over propylthiouracil (PTU) for initial treatment due to its once-daily dosing and lower incidence of adverse effects.
- Methimazole is associated with fewer side effects and ease of administration compared to PTU.
- Propylthiouracil inhibits peripheral deiodination of T4 to T3 and is recommended for use in the first trimester of pregnancy due to low placental transfer.
- Both thioamides, Methimazole and PTU, act by reducing hormone synthesis in the thyroid gland.
Iodide Therapy
- Iodide therapy is indicated for reducing size and vascularity of a hyperplastic thyroid gland, especially in preparation for surgery or thyroid storm.
- Chronic use of iodides during pregnancy should be avoided due to potential fetal toxicity.
- Iodides are contraindicated in hyperthyroid patients presenting with iodine-induced effects.
Adverse Reactions and Toxicities
- Severe hepatitis is a reported adverse reaction associated with PTU use.
- Agranulocytosis occurs in about 0.5%-1% of patients treated with thioamides.
- Iodides may cause adverse reactions such as iodism, characterized by symptoms like metallic taste and skin reactions.
- Chronic iodide therapy may lead to toxicity-related effects and is thus used cautiously.
Radioactive Iodine Treatment
- Radioactive iodine therapy is an effective treatment for hyperthyroidism and is contraindicated in pregnant or nursing women due to risks to the fetus or infant.
- Radioactive iodine is administered orally and is efficient for selective destruction of hyperactive thyroid tissue.
Thyroid Function and Metabolic Regulation
- Primary hypothyroidism typically results from autoimmune conditions like Hashimoto's thyroiditis.
- TSH Releasing Hormone (TRH) stimulates the secretion of TSH, regulating thyroid hormones.
- The primary function of T4 and T3 is to regulate metabolic processes, including energy expenditure, body temperature, and growth.
Patient Management Considerations
- Careful monitoring of thyroxine levels is required, especially in patients on medications like omeprazole that may affect absorption.
- Once weekly thyroxine injections may be effective for some patients to maintain stable hormone levels, particularly in those with adherence issues.
- Optimal TSH range for patients on levothyroxine therapy should be between 0.5 and 2.5 mIU/L.
Key Symptoms and Clinical Indicators
- Symptoms of hyperthyroidism can include weight loss, heat intolerance, and tachycardia.
- Inadequate levothyroxine replacement might be observed with elevated TSH levels in patients undergoing treatment.
Summary of Comparative Efficacy
- Levothyroxine is preferred for long-term thyroid hormone replacement due to its stable pharmacokinetics and lower risk of fluctuating hormone levels compared to liothyronine.
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Description
Test your knowledge on the transport and function of thyroid hormones, including the role of thyroxine-binding globulin (TBG), transthyretin, albumin, and lipoproteins. Explore topics such as the conversion of T4 to T3 by deiodinases in peripheral tissues and the evaluation of thyroid function.
