HYPERTHYROIDISM (GRAVE'S
DISEASE) EXOPTHALMIC GOITER
This is a hypermetabolic condition which is characterized by excessive amounts of thyroid hormone in the blood stream.
Incidence Affects women five times more frequently than men and peaks in incidence in the 3rd and 4th decades.
Causes
1. Unknown
2. Stress, Family History
3. Excessive output of thyroid hormones is thought to be due to abnormal stimulation of the thyroid gland by circulating immunoglobulins
4. It may appear after an emotional sheek, an infection or emotional stress.
5. It can also be the result of ingestion of excessive amounts of thyroid hormone medication (factitious hyperthyroidism)
Types
1. Grave's Disease (Most prevalent) diffuse hyperfunction of the thyroid gland with autoimmune etiology and associated-with-ophthalmopathy; most common in younger women; may subside spontaneously.
[Thyroid-stimulating Ab (TSAb), an immunoglobulin found in the blond of patients with Grave's disease, is capable of reacting with the receptor for TSH on the thyroid plasma membrane and of stimulating thyroid hormone production and secretion.
2. Toxic nodular goitre (single or multiple) more common in older women with preexisting goitre, will continue to be overactive unless eradicated or kept under suppressive therapy.
Pathophysiology
It is characterized by hypertrophy and hyperplasia of the thyroid gland, which is accompanied by increased vascularity and blood flow and enlargement of the gland. [Most of the clinical manifestation result from increased metabolic rate, excessive heat production, increased neuromuscular and cardiovascular activity and hyperactivity of the sympathetic nervous system
Hyperthyroidism ranges from a mild increase in metabolic rate to the severe hyperactivity known as thyrotoxicosis, thyroid storm or thyroid crisis.
Clinical Manifestations
1. Nervousness, emotional lability, irritability. Apprehension
2. Difficulty in sitting quietly.
3. Rapid pulse at rest and on exertion (ranges between 10 and 160), palpitations.
4. Heat intolerance, profuse perspiration; flushed sin (e.g. Hands may be warm, soft, moist).
5. Fine tremor of hands, change in bowel habits constipation or diarrhoea.
6. Increased appetite and progressive weight loss, frequent stools.
7. Muscle fatigability and weakness, amenorrhea.
8. Atrial fibrillation may occur.
9. Bulging eyes (exophthalmos) - produces a star led expression.
10. Thyroid gland may be palpable and a bruit may be auscultated over gland
[Course may be mild, characterized by remissions and exacerbations].
11. It may progress to emaciation, extreme nervousness, delirium, disorientation, thyroid storm or crisis and death.
12. Thyroid storm or crisis, an extreme form of hyperthyroidism, is characterized by hyperpyrexia, diarrhoea, dehydration, tachycardia, arrhythmias, extreme irritation, delirium, coma, shock and death if not adequately treated: May be precipitated by stress (surgery, infection) or inadequate prep ration for surgery in a patient with known hyperthyroidism
Diagnostic Evaluation
1. Elevated T3, T4
2. Elevated Serum T3 resin update
3. Radioactive iodine uptake scan may be elevated or below normal depending on the underlying cause of the hyperthyroidism
Management
Pharmacotherapy: inhibits one or more stages in hormone synthesis or hormone release, another goal may be to reduce the amount of thyroid tissue, thereby reducing hormone production.
1. Drugs that inhibit hormone formation.
a. Thionamides-propylthiouracil (PTU), methimazole (Tapazole).
b. Acts by depressing the synthesis of thyroid hormone by inhibiting peroxidase
c. Given in divided daily doses (every 8 hours).
d. Duration of treatment is determined by clinical criteria.
(i) Thyroid gland becomes smaller.
(ii). Uptakes of Th and T₁ are measured to determine adequacy of dose.
(iii) Treatment continued until patient becomes clinically euthyroid, this varies from 3 months to 1-2 years, if euthyroidism cannot be maintained without therapy, then radiation or surgery is recommended.
(iv) Therapy is withdrawn gradually to prevent exacerbation.
2. Drugs to control peripheral manifestations of hyperthyroidism.
a. Propranolol (Inderal)
(1) Acts as a B-adrenergic blocking agent.
(ii) Abolishes tachycardia, tremor, excess sweating, nervousness.
(iii) Controls hyperthyroid symptoms until antithyroid drugs or radioiodine can take effect.
b. Glucocorticoids decrease the peripheral conversion of T to T3, a more potent thyroid hormone.
Potassium iodide, Lugol's solution and saturated solution of K iodide (SSKI) are used in combination with antithyroid agents or ẞ-adrenergic blockers to prepare the patient with hyperthyroidism for surgery. These drugs reduce the activity of the thyroid hormone and the vascularity of the thyroid gland, making the surgical procedure safer. Solutions of 4 iodine and iodide compounds are more palatable in milk or fruit juice and are administered through a straw to prevent staining of the teeth [These compounds reduce the metabolic rate more rapidly than antithyroid drugs, but their action does not last as long]
Radioactive iodine - destroys overactive thyroid cells. Iodine concentrates in the thyroid gland, where it will destroy thyroid cells without jeopardizing other radiosensitive tissues. Over a period of weeks or months, those thyroid cells exposed to the Iodine will be destroyed, resulting in reduction of the hyperthyroid state and eventually hypothyroidism. Prior to treatment with Iodine, the patient receives antithyroid drugs for 6-18 months.
Surgical Interventions
1. The surgical removal of about 5 sixths of the thyroid tissue (subtotal thyroidectomy).
Before surgery, the patient is give propylthiouracil until signs of hyperthyroidism have disappeared, iodine is prescribed to reduce the size and vascularity of the goitre. It may be given in the form of Lugol's solution, potassium iodide or hydriodic acid.
[Patients receiving iodine medication must be watched for evidence of iodine toxicity (iodism), the appearance of which is the signal for immediate withdrawal of the drug. Symptoms of iodine including swelling of the buccal mucosa, excessive salivation, coryza and skin eruptions.]
Thyroidectomy for treatment of hyperthyroidism usually is scheduled within a few days alter the patient's basal metabolic rate has been reduced to normal.
Complications
1. Thioamide toxicity-(Agranulocytosis) may occur suddenly.
2. Hypothyroidism treatment is used. if overtreated with antithyroid medication or if radiation
3. Radiation thyroiditis [(a transient exacerbation of hyperthyroidism)] may occur as a result of leakage of thyroid hormone into the circulation from damaged follicles.
4. Infiltrative ophthalmopathy occurs in 50% of patients with Grave's disease. Features include exophthalmos, weakness of extra ocular muscles, lid edema, lid lag
Nursing Interventions
1. Encourage high-calorie, high-protein foods
2. Provide a quiet, calm environment at meals
3. Restrict stimulants (tea, coffee, alcohol)
4. Foods and fluids are selected to replace fluid lost through diarrhoea and diaphoresis.
5. Monitor IV infusion with prescribed to maintain fluid and electrolyte balance.
6. The patient's weight and dietary intake may be recorded to monitor nutritional status.
7. Determine the patient's food and fluid preferences
8. Provide a cool, comfortable environment for the patient and provide fresh bedding and gown as needed.
[The patient with hyperthyroidism frequently finds a normal room temperature too warning or often unbearably uncomfortably because of his exaggerated metabolic rate and heat production]
9. Give cool baths, provide cool or cold fluids and monitor body temperature to provide relief.
10. Avoid soap to prevent drying and use lubricant skin lotions to pressure points.
11. If the patient experiences eye changes secondary to hyperthyroidism, eye care and protection may become necessary. Instruct the patient how to in still eyedrops or ointment as prescribed to soothe the eyes and protect the exposed cornea.
12. Arrange for the patient to eat alone, avoid commenting on the large dietary intake of the patient and make sure that the patient receives sufficient food. [The patient may be embarrassed by the very large meals that he consumes as a result of his greatly increased metabolic rate).
13. Encourage the patient to verbalize concerns and fears about illness and treatment.
14. Assure the patient that emotional reactions are the result of the disorder and that with effective treatment those symptoms will be controlled.
15. Explain procedures in an unhurried, calm manner to the patient.
16. Limit visitors, avoid stimulating conversations [or television programs] Reduce stressors in the environment, reduce noise and lights. Promote sleep and relaxation through use of prescribed medications, massage and relaxations exercises.
17 Minimize disruption of the patient's sleep and rest by clustering nursing activities.
18. Repeat information and instruction whenever necessary. [The patient's hyperexcitability and shortened attention span]
