Drugs for Thyroid Disorders - Ch. 61 Flashcards
What 2 hormones does the thyroid gland secrete?
Triiodothyronine (T3)
Thyroxine (T4)
What is hypothyroidism?
Deficiency of thyroid hormone
-Reduced thyroid hormone production
What are the kinds of hypothyroidism?
Primary
Secondary
What is primary hypothyroidism?
Abnormality in the thyroid gland itself
What is secondary hypothyroidism?
Caused by another body system dysfunction
e.g,
Pituitary gland is dysfunctional and doesn’t secrete thyroid hormone
Hypothalamus does not secrete TRH
What is hypothyroidism in newborns and infants called?
Cretinism
What are symptoms of cretinism?
Low metabolic rate
Retarded growth and sexual development
Mental retardation
What are symptoms of hypothyroidism in adults?
Firm edema (myxedema)
Decreased metabolic rate
-intolarance to cold, weight gain
Slow heart rate
Loss of mental and physical stamina
Hair loss
Goiter
What is a gaiter?
Enlargement of thyroid gland
Results from overstimulation by elevated levels of TSH
-TSH elevated bc there is little or no thyroid hormone for negative feedback
When can the presence of a goiter occur?
Hypothyroidism and hyperthyroidism
-demonstartes excessive stimulation of thyroid gland in both cases
What is used to treat Hypothyroidism?
Levothyroxine (synthroid)
Liothyronine
What hormone is levothyroxine a synthetic version of?
Thyroid hormone T4
What is levothyroxine used for in relation to hypothyroidism?
Replacement therapy
-maintancement therapy preferred agent
How long might it take for levothyroxine to take its full effect?
4-6 weeks
What is the half life of Levothyroxine?
~7 days
What hormone is liothyronine a synthetic version of?
Thyroid hormone T3
What is liothyronine used for in relation to hypothyroidism?
Myxedema coma
-Has a quicker onset, shorter half life
When might synthetic thyroid hormone drugs be used?
Surgical removal of thyroids glands (thyroid replacement)
Destroyed by radioactive iodine in the treatment of thyroid cancer or hyperthyroidism
unknown causes of hypothyroidism
What adverse effects are associated with thyroid hormone agents?
Thyrotoxicosis (drug excess)
What are the signs of thyrotoxicosis?
Cardiac dysrhythmias (palpitations)
Tachycardia, angina, hypertension
Insomnia, termos, headache, anxiety
nausea, diarrhea
menstrual irregularities
Weight loss, sweating, heat intolerance
When should thyroid hormone agents be used with caution?
Patients with cardiac disease, hypertension
When should a patient take levothyroxine?
30-60 min before breakfast
-food decreases drug absorption
Many drugs decrease the absorption of thyroid hormone agents, what are some examples?
PPIs
Antacids
What are the types of Hyperthyroidism?
Graves disease (autoimmune)
Toxic nodule goiter
What causes graves disease?
Antibodies stimulate thyroid gland to secrete excessive amounts of T3 and T4
What can be present in someone with Graves disease?
Goiter
What is toxic nodule goiter?
Functionally autonomous nodules
e.g, Thyroid gland tumour
What can result because of hyperthyroidism?
Excessive thyroid hormone secretion can cause thyrotoxicosis
How is hyperthyroidism treated?
Radioactive iodine (131I)
Surgery to remove all or parts of thyroid gland
Antithyroid drugs
How does radioactive iodine (131I) treat hyperthyroidism?
Works by destroying thyroid gland
What are antithyroid drugs?
Thioamide derivatives
Examples of antithyroid drugs?
Methimazole
propylthiouracil (PTU)
What do antithyroid drugs do?
Prevent thyroid hormone synthesis
How long do antithyroid drugs take for full effect?
3-12 weeks
What should a patient taking antithyroid medications do?
Take at the same time each day to maintain consistent blood levels
When is methimazole use contraindicated?
1st trimester of pregnancy (PTU preferred)
What symptoms of overdose of thyroid hormone be monitored for?
Cold intolerance
Depression
Edema
