Wk 8. Thyroid Disorders Flashcards
What two hormones does the thyroid produce?
Triiodothyronine T3
Thyroxine T4
- Which thyroid hormone is converted in the periphery?
T4 is converted to T3
- Which thyroid hormone is more potent?
T3
- Describe the steps of thyroid hormone regulation. (TRH, TSH, T3, T4, negative feedback loop)
TRH from hypothalamus TSH from anterior pituitary T3 & T4 from thyroid inhibit TSH from anterior pituitary
- Describe the relationship of TSH levels to T3 and T4 levels.
Low T3 or T4 increases TSH, high T3 or T4 lowers TSH
- Describe common clinical signs and symptoms of hypothyroidism?
Goiter; puffy, expressionless face; cold/dry skin; brittle hair; hair loss from scalp & outer half of eyebrows; fatigue; irritability; depression; lack of concentration; cold intolerance; constipation; heavy menses; increased cholesterol
- Persons over 50 years of age may need what change in the initial dose of levothyroxine?
Lowered
- Discuss the effects on the fetus of maternal hypothyroidism in pregnancy. A person treated for hypothyroidism may need to increase the dose of levothyroxine by how much?
Decreased IQ and neuropsychological function of the child. Increase levothyroxine dose by up to 50%.
- Discuss the effects of congenital hypothyroidism in infants.
Mental retardation, large tongue, pot belly, dwarfish stature, derangement of growth - nerves, muscles, bone, teeth
- How long until levothyroxine reaches a plateau?
One month
- Levothyroxine should be given with or without food?
Without food
- Discuss the expected change in TSH when a patient is responding to levothyroxine.
TSH decreases to normal levels
- Describe the signs and symptoms of thyrotoxicosis.
Tachycardia, angina, tremor, nervousness, insomnia, hyperthermia, heat intolerance, sweating, abdominal cramping, weight loss, increased appetite, menstrual irregularities
- Which drugs can cause decreased absorption of levothyroxine? How many hours after the administration of levothyroxine may these drugs be given?
H2-recptor blockers, proton pump inhibitors, bile-acid sequestrants such as colestyramine (Questran) and colestipol (Colestid); sucralfate (Carafate); calcium, iron, magnesium, aluminum.
4 hours.
- Why would a nurse administer levothyroxine with caution to a patient on warfarin?
Levothyroxine increases the degradation of Vitamin K-dependent clotting factors and may increase the chance of bleeding. May need to decrease dose of warfarin.
- What is the interaction between catecholamines and levothyroxine?
Levothyroxine increases the body’s response to epinephrine, norepinephrine, and dopamine.
- Why might liothyronine (Cytomel) be given instead of levothyroxine (Levothyroid)?
Rapid onset of action in myxedema coma.
- Discuss the nursing care of a patient with hypothyroidism.
Life-long replacement; take on an empty stomach; monitor for hypothyroidism & hyperthyroidism; hold levothyroxine if pulse >100/min & call primary care provider; monitor TSH, T3 & T4; minimize adverse drug interactions; monitor warfarin levels.
- What are the symptoms of thyrotoxic crisis (thyroid storm)? What usually triggers it?
Restlessness, agitation, tremor, severe tachycardia, hypotension, heart failure, hyperthermia, profound weakness, unconsciousness, coma.
Severe illness or major surgery.
- What mimics TSH in patients with Grave’s Disease?
Thyroid-stimulating immunoglobulins (TSI)
- What are some signs and symptoms of Grave’s Disease?
Rapid, strong heartbeat; rapid thoughts & speech; trouble concentrating; tremor; insomnia; weakened muscles; increased body temperature; warm, moist skin; increased appetite with weight loss; diarrhea; exophthalmos.
- What TSH level is expected with hyperthyroidism?
Decreased TSH
- Give two ways propylthiouracil (PTU) works in hyperthyroidism?
Inhibits thyroid hormone synthesis by inhibiting peroxidase. Suppresses conversion of T4 to T3 in the periphery.
- Name a blood disorder caused by thionamides?
Agranulocytosis – may see sore throat or fever.
- What may happen to thyroid hormone production after the use of a thionamide?
Hypothyroidism
- How does Tapazole (methimazole) work differently from PTU?
Inhibits thyroid hormone synthesis, but does not block T4 or T3 in the periphery.
- LOW-dose iodine-131 causes which delayed adverse effect?
Hypothyroidism
- What precautions should be taken with persons undergoing HIGH-dose iodine-131?
Stay 3-6 feet from patient; only 30 min of contact per day; double flush urine and secretions down toilet; have patient increase fluids and void frequently.
- How does an iodine solution work?
Inhibits synthesis and release of thyroid hormones.
- At what heart rate would the nurse hold the levothyroxine and call the prescriber?
Hold if >100/min
