Download NURSING PROCESS FOCUS Clients Receiving Thyroid Hormone

ADAMMC43_0131756656 2/28/07 3:53 AM Page 669 TEAM-B ve401:PEQY046:phada2:ch43:
Chapter 43
PROTOTYPE DRUG
Levothyroxine (Synthroid)
Drugs for Pituitary, Thyroid, and Adrenal Disorders
669
Thyroid Hormone
ADVERSE EFFECTS
The difference between a therapeutic and a toxic dose of levothyroxine is
narrow, and care must be taken to avoid overtreatment. Adverse effects are
those of hyperthyroidism and include palpitations, dysrhythmias, anxiety,
insomnia, weight loss, and heat intolerance. Menstrual irregularities may
occur in females, and long-term use of levothyroxine has been associated
with osteoporosis in women.
Contraindications: This drug is contraindicated in clients with known or
suspected adrenal insufficiency, and in clients hypersensitive to the drug.
ACTIONS AND USES
Levothyroxine, a synthetic form of thyroxine (T4), is a drug of choice for replacement therapy in clients with low thyroid function. Actions are those of
thyroid hormone, and include loss of weight, improved tolerance to environmental temperature, increased activity, and increased pulse rate. Doses
are highly individualized. Therapy may take 3 weeks or longer before T4 levels stabilize; Doses may require periodic adjustments for several months.
Serum TSH levels are monitored to determine whether the client is receiving
sufficient levothyroxine—high TSH levels usually indicate that the dosage
of T4 needs to be increased.
INTERACTIONS
Drug–Drug: Cholestyramine and colestipol decrease the absorption of
levothyroxine. Concurrent administration of epinephrine and norepinephrine increases the risk of cardiac insufficiency. Use with oral anticoagulants
may potentiate hypoprothrombinemia.
Lab Tests: Unknown.
Herbal/Food: Lemon balm may interfere with thyroid hormone action.
Treatment of Overdose: Overdose can cause serious thyrotoxicosis, which
may not present until several days after the overdose. Treatment is symptomatic, usually targeted at preventing cardiac toxicity with beta-adrenergic
antagonists such as propranolol.
ADMINISTRATION ALERTS
■ Administer medication at the same time every day, preferably in the
morning to decrease incidence of drug-related insomnia.
■ Pregnancy category A.
PHARMACOKINETICS
Onset: Unknown
Peak: 3–4 wk
Half-life: 6–7 days
Duration: 1–3 wk
See the Companion Website for a Nursing Process Focus
specific to this drug.
NURSING PROCESS FOCUS Clients Receiving Thyroid Hormone Replacement
Assessment
Potential Nursing Diagnoses
Prior to administration:
Obtain a complete health history including weight, allergies, drug history, and
possible drug interactions.
Obtain a complete physical examination.
Assess for the presence and history of symptoms of hypothyroidism.
Obtain ECG and laboratory studies including T4, T3, and serum TSH levels.
■
■
■
■
■
■
Activity Intolerance, related to disease process
Fatigue, related to impaired metabolic status
Knowledge, Deficient, related to drug therapy
Health Maintenance, Ineffective, related to side effects of drug
■
■
Planning: Client Goals and Expected Outcomes
The client will:
Exhibit normal thyroid hormone levels.
Report a decrease in hypothyroid symptoms.
Experience no significant adverse effects from drug therapy.
Demonstrate an understanding of the drug’s action by accurately describing drug side effects and precautions.
■
■
■
■
Implementation
Interventions and (Rationales)
■
■
■
Monitor vital signs. (Changes in metabolic rate are manifested as changes in
blood pressure, pulse, and body temperature.)
Monitor for decreasing symptoms related to hypothyroidism such as fatigue,
constipation, cold intolerance, lethargy, depression, and menstrual irregularities.
(Decreasing symptoms demonstrate that drug is achieving therapeutic affect.)
Monitor for symptoms related to hyperthyroidism such as nervousness, insomnia,
tachycardia, dysrhythmias, heat intolerance, chest pain, and diarrhea. (Symptoms
of hyperthyroidism indicate the drug is at a toxic level.)
Client Education/Discharge Planning
■
Instruct client to report dizziness, palpitations, and intolerance to temperature
changes.
■
Instruct client about the signs of hypothyroidism and to report symptoms.
■
Instruct client about the signs of hyperthyroidism and to report symptoms.
(Continued)
ADAMMC43_0131756656
670
Unit 8
2/19/07
10:08 AM
Page 670
The Endocrine System
NURSING PROCESS FOCUS Clients Receiving Thyroid Hormone Replacement (Continued)
Implementation
Interventions and (Rationales)
■
Client Education/Discharge Planning
Monitor T3, T4, and TSH levels. (These levels help determine the effectiveness
of pharmacotherapy.)
Instruct client:
About the importance of ongoing monitoring of thyroid hormone levels.
To keep all laboratory appointments.
■
■
■
■
Monitor blood glucose levels, especially in individuals with diabetes mellitus.
(Thyroid hormone increases metabolic rate, and glucose utilization may be
altered.)
Instruct the diabetic client:
To monitor blood glucose levels.
Adjust insulin doses as directed by the healthcare provider.
Provide supportive nursing care to cope with symptoms of hypothyroidism
such as constipation, cold intolerance, and fatigue until drug has achieved
therapeutic effect. (Supportive nursing care decreases the client’s anxiety,
which will promote healing and compliance.)
Instruct client to:
Increase fluid and fiber intake and activity to reduce constipation.
Wear additional clothing and maintain a comfortable room environment for
cold intolerance.
Plan activities and include rest periods to avoid fatigue.
■
■
■
■
■
■
■
Monitor weight at least weekly. (Weight loss is expected because of increased
metabolic rate. Weight changes help determine the effectiveness of drug
therapy.)
Monitor client for signs of decreased compliance with therapeutic regimen.
(Decreased compliance requires early intervention and education about the
medical regimen and the disease process.)
■
Instruct client to weigh self weekly and to report significant changes.
Instruct client about:
The importance of lifelong therapy.
The disease.
The importance of follow-up care.
■
■
■
Evaluation of Outcome Criteria
Evaluate the effectiveness of drug therapy by confirming that client goals and expected outcomes have been met (see “Planning”).
The client’s thyroid hormone levels are normal.
The client demonstrates decreased symptoms of hypothyroidism.
The client is free from significant adverse effects from drug therapy.
The client demonstrates an understanding of the drug’s action by accurately describing drug side effects and precautions.
■
■
■
■
See Table 43.3, under the heading “Thyroid Agents,” for a list of drugs to which these nursing actions apply.
Do not take other prescribed drugs, OTC medications,
herbal therapies, or dietary supplements without notifying your healthcare provider.
● Keep all scheduled appointments and laboratory visits
for testing.
●
ANTITHYROID AGENTS
Medications are often used to treat the cause of hyperthyroidism or to relieve its distressing symptoms. The goal of antithyroid therapy is to lower the activity of the thyroid gland.
43.7 Pharmacotherapy
of Hyperthyroidism
Hypersecretion of thyroid hormone results in symptoms
that are the opposite of those caused by hypothyroidism: increased body metabolism, tachycardia, weight loss, elevated
body temperature, and anxiety. The most common type of
hyperthyroidism is called Graves’ disease. Considered an
autoimmune disease in which the body develops antibodies
against its own thyroid gland, Graves’ disease is four to eight
times more common in women, and most often occurs be-
tween the ages of 30 and 40. Other causes of hyperthyroidism
are adenomas of the thyroid, pituitary tumors, and pregnancy.
If the cause of the hypersecretion is found to be a tumor, or if
the disease cannot be controlled through pharmacotherapy,
surgical removal of the thyroid gland is indicated.
The two primary drugs for hyperthyroidism, propylthiouracil (PTU) and methimazole (Tapazole), are called
thioamides. These agents act by inhibiting the incorporation
of iodine atoms into T3 and T4. Methimazole has a much
longer half-life that offers the advantage of less frequent
dosing, although side effects can be more severe. Both
thioamides are pregnancy category D agents, but methimazole crosses the placenta more readily than propylthiouracil
and is contraindicated in pregnant clients.
A third antithyroid drug, sodium iodide-131 (Iodotope) is
a radioactive isotope that destroys overactive thyroid glands
with ionizing radiation. Shortly after oral administration, I131 accumulates in the thyroid gland, where it destroys follicular cells. The goal of pharmacotherapy with I-131 is to
destroy just enough of the thyroid gland so that levels of thyroid function return to normal. Full benefits may take several
months. Although most clients require only a single dose,
others need multiple treatments. Small diagnostic doses of