Thyroid & Antithyroid Drugs Flashcards
Functions of the Thyroid gland
Secretes hormones essential for proper regulation of metabolism -Thyroxine (T4) -Triiodothyronine (T3) Thyroid Stimulating Hormone (TSH) -Triggers T3 & T4 if needed
Thyroid Hormone Functions
- Metabolism
- Contribute to normal growth and development (Brain & Body)
- Control heat-regulating system
- Effects on Cardiovascular, Endocrine and Neuromuscular systems
Hypothyroidism is
Deficiency of thyroid hormones
How many types of hypothyroidism is there
3
The stages of Hypothyroidism
Congenital Hypothyroidism (cretinism)
Hypothyroidism (adult)
Goiter
Congenital Hypothyroidism general info
Occurs in infants/children
Causes low metabolic rate, retarded growth and sexual development, mental retardation
Hypothyroidism general info
- Myxedema (Severe hypothyroidism)
- Causes decreased metabolic rate, loss of mental and physical energy/stamina, weight gain, brittle hair loss of hair, lower heart rate, constipation
- Complain of lethargy, fatigue, and cold intolerance
Goiter general info
Thyroid enlargement due to reduced levels of T3 & T4 Excessive TSH release
Thyroid replacement prototype drug
Levothyroxine (Synthroid, Levothyroid)
What does Levothyroxine do?
- Thyroid preparations are given to replace what the thyroid gland cannot produce to achieve normal thyroid levels (euthyroid)
- Thyroid drugs work the same way as thyroid hormones
Levothyroxine Indications
Hypothyroidism
Thyroidectomy
Levothyroxine is given in what forms?
IV & PO (micrograms)
Levothyroxine drug effects
- Increase metabolic rate & protein synthesis
- Increase cardiac output, renal perfusion and oxygen use
- Increase body temperature and blood volume
- Increase overall growth
Levothyroxine contraindications
- Allergy
- Recent Myocardial Infarction
- Other Cardiac Problems: Angina, Hypertension (Use cautiously)
- Hyperthyroidism
Levothyroxine interactions
- Decreased Levothyroxine effectiveness
- Phenytoin, Fosphenytoin, Phenobarbital - Reduced effectiveness of Insulin
- Antidiabetic oral drugs cause Hyperglycemia - Reduced levothyroxine absorption
- Binding agents (Cholestyramine, antacids, calcium supplements, Sucralfate)
- Give 3 hours apart
Levothyroxine adverse effects
Similar to signs/symptoms of Hyperthyroidism
CNS
Anxiety, insomnia, tremors, headache
CV
Tachycardia, palpitations, angina, hypertension, dysrhythmias
GI
Nausea, diarrhea, weight loss, appetite changes
Other
Menstrual Irregularities, sweating, heat intolerance
What to monitor for with Levothyroxine
TSH
Sometimes T4
Should Levothyroxine be used during pregnancy?
Yes.
Fetal growth may be retarded if maternal hypothyroidism is untreated during pregnancy
Adjust dosage every 4 weeks to keep TSH at the lower end of the normal range
Taking Levothyroxine in the morning reduces the likelihood of
Insomnia
Should brands of levothyroxine be switched?
Not without physician approval
How long does it take for therapeutic effects of Levothyroxine?
Several Months
What is Hyperthyroidism?
Excessive thyroid hormone secretion
Diseases / conditions that cause hyperthyroidism
Graves’ disease
-Autoimmune
-Most Common Form; Affects women 20-40
years of age
-Causes Exophthalmos(bulging eyes)
Plummer’s disease (rare)
-Also called toxic nodular disease
Thyroid storm (induced by stress or infection)
-Severe and potentially life-threatening
What does Hyperthyroidism affect?
Affects multiple body systems, resulting in an overall increase in metabolism
CNS
-Irritability, Nervousness, Fatigue, Sleep disorders
CV
-Palpitations
GI
-Diarrhea, Increased appetite
Other
-Muscle weakness, Altered menstrual flow,
Flushing, Heat Intolerance
