Thyroid & Antithyroid Drugs

Question 1

Functions of the Thyroid gland

Answer 1

Secretes hormones essential for proper regulation of metabolism
   -Thyroxine (T4)
   -Triiodothyronine (T3)
Thyroid Stimulating Hormone (TSH)
   -Triggers T3 & T4 if needed

Question 2

Thyroid Hormone Functions

Answer 2

• Metabolism
• Contribute to normal growth and development (Brain & Body)
• Control heat-regulating system
• Effects on Cardiovascular, Endocrine and Neuromuscular systems

Question 3

Hypothyroidism is

Answer 3

Deficiency of thyroid hormones

Question 4

How many types of hypothyroidism is there

Answer 4

3

Question 5

The stages of Hypothyroidism

Answer 5

Congenital Hypothyroidism (cretinism)
Hypothyroidism (adult)
Goiter

Question 6

Congenital Hypothyroidism general info

Answer 6

Occurs in infants/children

Causes low metabolic rate, retarded growth and sexual development, mental retardation

Question 7

Hypothyroidism general info

Answer 7

• 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

Question 8

Goiter general info

Answer 8

Thyroid enlargement due to reduced levels of T3 & T4  Excessive TSH release

Question 9

Thyroid replacement prototype drug

Answer 9

Levothyroxine (Synthroid, Levothyroid)

Question 10

What does Levothyroxine do?

Answer 10

• 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

Question 11

Levothyroxine Indications

Answer 11

Hypothyroidism

Thyroidectomy

Question 12

Levothyroxine is given in what forms?

Answer 12

IV & PO (micrograms)

Question 13

Levothyroxine drug effects

Answer 13

• Increase metabolic rate & protein synthesis
• Increase cardiac output, renal perfusion and oxygen use
• Increase body temperature and blood volume
• Increase overall growth

Question 14

Levothyroxine contraindications

Answer 14

• Allergy
• Recent Myocardial Infarction
• Other Cardiac Problems: Angina, Hypertension (Use cautiously)
• Hyperthyroidism

Question 15

Levothyroxine interactions

Answer 15

• 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

Question 16

Levothyroxine adverse effects

Answer 16

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

Question 17

What to monitor for with Levothyroxine

Answer 17

TSH

Sometimes T4

Question 18

Should Levothyroxine be used during pregnancy?

Answer 18

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

Question 19

Taking Levothyroxine in the morning reduces the likelihood of

Answer 19

Insomnia

Question 20

Should brands of levothyroxine be switched?

Answer 20

Not without physician approval

Question 21

How long does it take for therapeutic effects of Levothyroxine?

Answer 21

Several Months

Question 22

What is Hyperthyroidism?

Answer 22

Excessive thyroid hormone secretion

Question 23

Diseases / conditions that cause hyperthyroidism

Answer 23

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

Question 24

What does Hyperthyroidism affect?

Answer 24

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

Question 25

Types of Hyperthyroidism treatment

Answer 25

Radioactive iodine, Surgery to remove thyroid, Antithyroid drugs

Question 26

Antithyroid prototype drug

Answer 26

Propylthiouracil (PTU)

Question 27

Propylthiouracil works by

Answer 27

Inhibits thyroid hormone synthesis
Inhibit the conversion of T4 to T3
Cannot inactivate already existing thyroid hormone in circulation

Question 28

Propylthiouracil therapeutic effects take how long & is available by what form

Answer 28

1-2 weeks

PO

Question 29

Propylthiouracil contraindications

Answer 29

Allergy

Pregnancy Cat. D

Question 30

Propylthiouracil adverse effects

Answer 30

Agranulocytosis
Liver toxicity
Hypothyroidism Symptoms

Question 31

Propylthiouracil nursing implications

Answer 31

Better tolerated when given with food

Give at the same time each day to maintain consistent blood levels

Question 32

Stopping Propylthiouracil abruptly can cause

Answer 32

Thyroid Storm
Signs: Hyperthermia (105° F or higher), severe tachycardia, restlessness, agitation, tremor, unconsciousness, coma, hypotension, heart failure

Question 33

What should be monitored for when using Propylthiouracil?

Answer 33

-Agranulocytosis
-CBC
-Report any fever, sore throat, mouth
ulcers/sores, unusual bleeding
-Monitor Liver function

Question 34

Expected therapeutic response of Propylthiouracil

Answer 34

Weight gain
Decreased pulse
Decreased T4
Absence of hyperthyroidism symptoms