Thyroid & Parathyroid Agents Flashcards
What are the actions of the Thyroid gland?
- Produces two thyroid hormones using iodine found in the diet:
- Tetraiodothyronine or levothyroxine (T4)
-Triiodothyronine or liothyronine (T3)
Removes iodine from the blood, concentrates it, and prepares it for attachment to tyrosine, an amino acid.
Which are the two Thyroid Hormones produced?
Tetraiodothyronine (T4 - ‘tetra means 4) ) & Triiodothyronine (T3 - ‘Tri’ means 3)
What is another name for Tetraiodothyronine ( T4)
Levothyroxine - synthetic
What is another name for Triiodothyronine ( T3)
Liothyronine
Apart from Thyroid Hormone, what other hormone does the Thyroid produce?
Calcitonin
What are the function of Thyroid Hormones (TH) in our body ?
- Regulate the rate of metabolism
- Affect heat production and body temperature
- Affect oxygen consumption, cardiac output, and blood volume
- Affect enzyme system activity
- Affect metabolism of carbohydrates, fats, and proteins
- Regulate growth and development
What are the two types of Thyroid Dysfunction?
Hypothyroidism (underactive) & Hyperthyroidism (overactive)
Which one is the most common in patients. Hypothyroidism or Hyperthyroidism?
Hypothyroidism.
Explain Hyperthyroidism.
Excessive amounts of thyroid hormones are produced and released into the circulation
* Cause : Graves’ disease - most common cause.
What are the signs and symptoms of hyperthyroidism?
Increased body temperature, tachycardia, thin skin, palpitations, hypertension, flushing, intolerance to heat, amenorrhea (absence of menstrual cycle), weight loss, and goiter (swelling in the neck that occurs when the thyroid gland enlarges due to THS stimulation)
What is the cause of Hypothyroidism?
Causes:
Absence of the thyroid gland either born without it or removed surgically.
Lack of sufficient iodine in the diet to produce the needed level of thyroid hormone
Lack of sufficient functioning of thyroid tissue due to tumor or autoimmune disorders (Hashimoto most common)
Lack of TSH (Thyroid Stimulating Hormone) due to pituitary disease
Lack of TRH (Thyroid Releasing Hormone) related to a tumor or disorder of the hypothalamus
What are the signs and symptoms of Hypothyroidism?
Can be varied and vague, such as obesity and fatigue, weight gain, eyelid edema, feeling cold, hair loss.
What are some lifespan considerations that we need to take into account when giving Thyroid and Parathyroid agents to children?
Hypothyroidism: we will use Levothyroxine
Higher doses - due to higher metabolism.
Monitor thyroid labs
Monitor growth and development
Hyperthyroidism : Methimazole
Don’t use: Propylthiouracil (PTU) or Radioactive agents
Hypercalcemia usually only seen in children with cancer and we can use Bisphosphonates to treat.
Monitor calcium levels closely when using.
What are some lifespan considerations that we need to take into account when giving Thyroid and Parathyroid agents to adults?
Hypothyroidism:
Thyroid replacement therapy is lifelong (Educate)
Levothyroxine is the drug of choice incl pregnancy and lactation.
Hyperthyroidism:
Side effects worse with methimazole such as bone marrow depression, GI and CNS effect.
Sodium iodide can affect fertility.
Pregnancy: Propylthiouracil (PTU) due to less drug passes through the placenta.
Do not use in lactation
Hypercalcemia:
Taken for Osteoporosis
Monitor calcium levels
Pregnancy: Do not use bisphosphonate
What specific condition can happen to the infant if mom is taking Hyperthyroidism agents during pregnancy or lactation ?
Creatininsm
What are some lifespan considerations that we need to take into account when giving Thyroid and Parathyroid agents to older adults?
Hypothyroidism :
Levothyroxine drug of choice.
Screen regularly
Start low, go slow
- Hyperthyroidism :
Sodium iodide usually drug of choice due to less adverse effects.
Monitor for hypothyroidism
Hypercalcemia:
Dietary deficiencies: Calcium and vit D supplements
Osteoporosis: Bisphosphonates can help move calcium back to bone.
Renal impairment
Monitor calcium levels
What are the drug classes that we need to remember for Thyroid Hormones?
- Levothyroxine
- Liothyronine
- Liotrix
- Thyroid Desiccated
Which Thyroid Hormone Agent is made out of dried animal Thyroid tissue, in particular Pig ?
Thyroid Desiccated
How does the Thyroid Hormones work on the body?
Increases the metabolic rate of body tissues which increases oxygen consumption, respirations, heart rate, rate of fat, protein and carbohydrate metabolism. - ultimately affecting our growth and maturation.
Increases cellular metabolism in all areas of our body.
What are the indications for Thyroid Hormones?
- Hypothyroidism
- Myxedema coma
- Pituitary TSH suppression in the treatment of euthyroid goiters
- Management of thyroid cancer;
- Thyrotoxicosis in conjunction with other therapy
What is Myxedema coma?
Severe hypothyroidism that leads to decreased mental status, hypothermia and other symptoms r/t the functioning and slowing of other organs, It is a medical emergency and there is a high mortality rate associated with it.
What is the difference between Hypothyroidism and Myxedema coma?
With Hyperthyroidism our organisms are still working whereas with Myxedema coma they are starting to not work.
What is Thyrotoxicosis?
A Hyperthyroidism where we see signs and symptoms. We would treat this with hyperthyroid medication to try to stop the negative feedback loop that is increasing the thyroid hormone levels. Decreasing the release of TSH should therefore reduce the TH levels.
To treat Thyrotoxicosis would we give them thyroid hormone alone?
No, that would end up making the Hyperthyroidism worse
What is an absolute contraindication of Thyroid Hormones?
Allergy
What are some relative contraindication of Thyroid Hormones?
Acute MI - however if they have hypothyroidism that is complicating their heart, then we would give medication.
Thyrotoxicosis - however, this is sometimes treated by using the negative feedback loop with anti-hyperthyroid medications in conjunction with other medications.
What are some known cautions to consider in relations to Thyroid Hormones?
Hypoadrenal conditions such as Addison’s Disease because the body cannot handle the drug effect.
What are some known adverse reactions to Thyroid Hormones?
NONE - Very very rare.
- Skin reactions - usually only in the beginning.
- Symptoms of hyperthyroidism
- Cardiac stimulation
- CNS effect
Are there any DDI’s to Thyroid Hormones, and if so, what are they?
- Oral anticoagulants - increased risk of bleeding
- Digoxin - Decreased Digoxin level.
- Theophylline - Decreased clearance of Theophylline.
Before giving a patient TH, what do we need to assess?
- History : cautions/contraindications (heart attack. Hypoadrenal state/Addison’s , family history
- Physical : Baseline status - Assess skin; CNS; vitals & ECG
- Monitor appropriate labs - Thyroid function test.
What nursing diagnosis should we be prepared for before giving TH’s?
- Decreased Cardiac Output r/t cardiac effect.
- Malnutrition risk: less than body requirements r/t changes in metabolism
- Altered tissue perfusion r/t Thyroid activity
- Knowledge deficit
What implementations should we be prepared for when we’ve give a patient TH’s?
- Administration: single daily dose 30-60 minutes before breakfast each day to keep blood levels consistent.
- Administer with a full glass of water.
- Do not administer other drugs at the same time
- Monitor response carefully when beginning therapy, especially cardiac response - may take 6 weeks to work.
- Monitor for cardiac response to detect any adverse cardiac effects.
- Arrange for periodic blood tests of Thyroid functioning
- Patient teaching
What are the Antithyroid Agents that we need to know?
- Thiomides : Propylthiouracil (PTU) & Methimazole
- Iodine Solutions : Strong iodine solution, Potassium iodide & Sodium iodide I131 and I123
What are the agents that we need to know for Thiomides?
Propylthiouracil (PTU)
Methimazole
What are the agents that we need to know for iodine solutions?
Strong iodine solution
Potassium iodide
Sodium iodide I131 and I123 (radioactive)
How does Thiomides work?
Prevents the formation of Thyroid Hormone within the Thyroid cells which lowers the serum levels.
Why would you give patients Thiomides ?
For Hyperthyroidism
Why would you give patients Iodine Solutions ?
- Indication for low dose: diagnosis/evaluate thyroid function
- Indication for high dose: hyperthyroidism, radiation emergencies
Which Iodine Solutions are most commonly used?
Strong Iodine Solution and Potassium Iodine.
Which Iodine Solutions are usually reserved for radiation emergencies, for women who cannot become pregnant because the detrimental effect of radiation on the fetus or for older adults not candidates for surgery ?
Sodium Iodine I 131 & I 123
How does Iodine Solutions work on the body?
Enters thyroid cells and destroys them by giving off radiation
In low doses, what can Iodine Solutions be used for?
Diagnose or evaluate thyroid function.
In high doses, what can Iodine Solutions be used as?
To treat Hyperthyroidism and radiation emergencies.
Why would you give patients Strong iodine solution & potassium iodide ?
hyperthyroidism, radiation emergencies, suppression of thyroid gland before surgery, acute thyrotoxicosis.
How does Strong iodine solution & potassium iodide work on the body ?
High doses saturate the thyroid cells preventing thyroid hormone formation.
What is an absolute contraindication with giving a patient Antithyroid agents?
Allergy
What conditions should we be cautious of when giving patient Antithyroid agents?
Propylthiouracil (PTU ) : Liver impairment
What are some known adverse reactions that patients may experience when taking Antithyroid Agents?
- All: hypothyroidism
- Methimazole: bone marrow suppression
- PTU: severe liver toxicity
- Iodine Solutions: Iodism
Are there any DDI’s with Antithyroid agents, and if so, what are they?
- Oral anticoagulants
- Theophylline
- Beta-blockers
- Digoxin
Why is it so important to ensure that we do scheduled check ups when patients are taking Antithyroid hormones in relation to other medications?
Hyperthyroidism can often lead to Hypothyroidism and this can severely effect how other drugs are metabolized in the body.
What should we be assessing prior to giving Antithyroid agents?
- History : Allergy, liver impairment
- Physical Assess : skin; CNS; vitals & ECG
- Labs: thyroid function, CBC, liver function, pregnancy (PTU)