Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
53 Cards in this Set
- Front
- Back
|
Which thyroid hormone is more active at activating the thyroid receptor in vivo?
|
T3
|
|
|
T3 and T4 are reversibly bound to which protein in the blood?
|
Thyroxine binding globulin
|
|
|
End-stage, life-threatening complication of hypothyroidism.
|
Myxedema coma
|
|
|
What causes primary hypothyroidism?
|
Gland destruction
(congenital, surgical, or medical therapies) |
|
|
What causes secondary hypothyroidism?
|
Inhibition of TSH secretion
|
|
|
What causes tertiary hypothyroidism?
|
Inhibition of TRH secretion from hypothalamus
|
|
|
Enlargement of the thyroid gland without excessive TH production results in..?
What causes this enlargement? |
Nontoxic goiter
Mainly caused by excessive TSH stimulation from inadequate TH synthesis |
|
|
What is an endemic goiter usually caused by?
|
In the U.S., it is most commonly seen in Hashimoto's thyroiditis
*Otherwise, caused by iodide deficiency |
|
|
What causes a sporadic goiter?
|
Drugs that inhibit the oxidation of iodine
|
|
|
List some symptoms seen with hypothyroidism.
|
1. Fatigue
2. Myxedema (dry flaky skin) 3. Weight gain 4. Edema 5. Slow speech |
|
|
List 3 agents used to treat hypothyroidism.
|
(Thyroid replacement hormones)
1. Thyroid U.S.P (dessicated thyroid) 2. Liotrix (fixed ratio preparation) 3. Levothyroxine (T4) |
|
|
Thyroid U.S.P is usually from what sort of source?
|
Bovine
|
|
|
What is an advantage of Thyroid U.S.P?
What's a disadvantage? |
It's cheap
It has variable activity |
|
|
What is Liotrix?
|
Fixed preparation ratio (T3/T4) used for hypothyroidism
|
|
|
What is a disadvantage of Liotrix?
|
T3 is not needed. T3 alone causes significant adverse effects (tremor, HA, palpitations, diarrhea)
|
|
|
What is the drug of choice for hypothyroidism?
|
Levothyroxine (T4)
|
|
|
What is an advantage of Levothyroxine?
|
It has fairly predictable results and lacks the adverse T3 effects seen with Liotrix.
|
|
|
How long does it take to see clinical improvement in symptoms after beginning Levothyroxine?
|
> 2 weeks
(full resolution may take 3-6 months) |
|
|
What sort of adverse effects can be caused by taking thyroid replacement therapies for hypothyroidism?
How can this be avoided? |
May have hyperthyroid-like adverse effects
*Serum T4 and TSH levels should be monitored bi-weekly for first 2 months of treatment. |
|
|
What are some signs and symptoms associated with hyperthyroidism?
|
1. Toxic goiter
2. Nervousness 3. Irritability 4. Weight loss 5. Increased appetite 6. Palpitations and tachycardia 7. Ptosis 8. Periorbital edema |
|
|
Grave's disease occurs most frequently in which individuals?
|
Young women
|
|
|
What is the cause of Grave's disease?
|
Autoimmune
(lymphocytes secrete Thyroid Stimulating Ig (TSI), which bind to TSH receptor and turns on the gland) |
|
|
Plummer's disease usually occurs in what type of individuals?
|
Patients > 50 yo
|
|
|
What is a life-threatening complication of hyperthyroidism?
|
Thyroid storm
(sudden exacerbation of hyperthyroidism--rapid and extensive release of T3 and T4) |
|
|
What are the goals of treatment for hyperthyroidism?
|
1. Symptomatic relief (beta-blockers)
2. Definitive treatment of problem (antithyroid agents) |
|
|
List 4 general classes of antithyroid agents.
|
1. B-adrenergic blockers
2. Thiomides 3. Radioactive iodine 4. Iodides |
|
|
Why are B-blockers used for hyperthyroidism?
|
To relieve symptoms
(tachycardia, sweating, tremor, nervousness) |
|
|
Which medication is most widely used in the treatment of thyrotoxicosis and a thyroid storm?
|
Propanolol
(B-blocker) |
|
|
What is the mode of action of thioamides?
|
Inhibit oxidation and coupling steps of biosynthesis of thyroid hormones
|
|
|
What is Methimazole?
|
Thioamide
(used for hyperthyroidism) |
|
|
What is Propylthiouracil?
|
Thioamide
(used for hyperthyroidism) |
|
|
Why do thioamides resolve symptoms so slowly?
|
They block the biosynthesis of thyroid hormones rather than the release
|
|
|
What is an advantage of Methimazole over Propylthiouracil?
|
Methimazole is excreted more slowly, so it is considered more potent that PTU
|
|
|
In what case is PTU a better choice of therapy than Methimazole?
Why? |
Pregnancy
*It is more strongly protein-bound and crosses the placenta less readily |
|
|
What rare, fatal adverse effect can occur with thioamides, especially with methimazole?
|
Agranulocytosis
|
|
|
How does radioactive iodine treat hyperthyroidism?
|
Radioactive iodine (131 I) is taken up by thyroid and destroys the T4 producing cells, leading to decreased TH production
|
|
|
What is a major advantage of using radioactive iodine for hyperthyroidism?
|
High cure rate (100%)
|
|
|
What are some disadvantages of radioactive iodine?
|
1. Chance of delayed hypothyroidism (years after treatment)
2. Multiple doses may be required 3. Response is hard to evaluate |
|
|
Radioactive iodine is contraindicated for which individuals?
|
1. Pregnant women
2. Nursing mothers |
|
|
What is the mode of action of iodides in treating hyperthyroidism?
|
1. Inhibition of organification and hormone release
2. Decrease the size and vascularity of the gland |
|
|
Iodides have a rapid onset of action-- the onset begins after how many days?
|
2 - 7 days
|
|
|
What is the pharmacological dose of Iodides to inhibit T3/T4 release?
|
>6 mg/ day
|
|
|
Other than B-blockers, which medication is valuable in treating a thyroid storm?
|
Iodide
|
|
|
Which medication is valuable for treating hyperthyroidism and in preoperative preparation for surgery?
|
Iodide
|
|
|
What is a major disadvantage of iodide therapy?
|
Increases intraglandular stores of iodine; should be given after onset of thioamide therapy.
|
|
|
Can iodide therapy be used alone?
|
No, it should not be used alone.
|
|
|
Which medication results in adverse reactions such as acneiform rashes, swollen salivary glands, mucous membrane ulceration, and a metallic taste?
|
Iodide
|
|
|
When using Levothyroxine, what lab values should be checked regularly?
|
Serum TSH and free thyroxine
|
|
|
Levothyroxine should be prescribed in a reduced dose for which patients?
|
1. Older patients
2. Patients with cardiac disease 3. Long-standing hypothyroidism |
|
|
How should myxedema coma be treated?
|
IV Levothyroxine
|
|
|
Describe the drug treatments used before and after a thyroidectomy.
|
1. Antithyroid drugs used until euthyroid status
2. K+ Iodide given 2 weeks prior to surgery to reduce vascularity of the gland 3. Usually thyroid supplementation is used following surgery |
|
|
What is the mechanism of action of Methimazole?
|
Inhibits iodide uptake and organification of iodine
|
|
|
What is the mechanism of action of Propylthiouracil?
|
Inhibits iodine organification AND inhibits peripheral conversion of T4 to T3 (type II deiodinase)
|
