HYPERTHYROIDISM

HYPERTHYROIDISM – Etiology, Pathophysiology, Symptoms, Complications, Clinical Features, Diagnostic Evaluation and Management

Hyperthyroidism is a condition in which thyroid gland produces too much of the hormone thyroxine, characteristic by elevated T₃  and T₄ level that result in accelerate body’s metabolism, causing sudden weight loss, a rapid or irregular heartbeat, sweating, and nervousness or irritability.

ETIOLOGY

• Grave’s disease: Grave’s disease, an autoimmune disorder in which antibodies produced by immune system stimulate thyroid to produce too much T₄, is the most common cause of hyperthyroidism. It may lead to graves ophthalmopathy and graves dermopathy.
• Hyper functioning thyroid nodules (toxic adenoma, toxic multinodular goiter, Plummer’s disease): hyperthyroidism occurs when one or more adenomas of thyroid produce too much T₄.
• Thyroiditis: thyroid gland can become inflamed for unknown reasons. The inflammation can cause excess thyroid hormone stored in the gland to leak into bloodstream. It may be subacute thyroiditis or postpartum thyroiditis.

Pathophysiology

Any disturbance in the normal homeostatic mechanism at hypothalamus and pituitary gland leads to hypersecretion of thyroid hormone. It may occur due to certain tumor or a defect of thyroid gland that may lead to hypersecretion of T₃ and T_4.  Hypersecretion of T₃ and T₄ lead to hypermetabolism state.

Hypersecretion of T₃ and T₄ —- increase degradation of protein, carbohydrate and fat —- increase fuel consumption —- increase BMR —- increasing rate of catabolism —- weight loss and excess heat production —- heat intolerance —- palpitation and excessive sweating

SYMPTOMS

Hyperthyroidism can mimic other health problems, which may make it difficult to diagnose. It can also cause a wide variety of signs and symptoms.

• Sudden weight loss
• Rapid heartbeat (tachycardia)
• Increased appetite
• Nervousness anxiety and irritability
• Tremor
• Sweating
• Changes in menstrual patterns
• Increased senstitivity to heat
• Changes in bowel patterns
• An enlarged thyroid gland (goiter)
• Fatigue, muscle weakness
• Difficulty sleeping
• Skin thinning
• Fine, brittle hair
• Exophthalamus
• Fast tendon reflex
• Reduce eye movement

COMPLICATIONS

• Heart problems: these include a rapid heart rate, a heart rhythm disorder called atrial fibrillation and congestive heart failure
• Brittle bones: untreated hyperthyroidism can also lead to weak, brittle bones (osteoporosis) because of over secretion of calcitonine

Eye problems: Grave’s ophthamlopathy characterized by bulging, red or swollen eyes, sensitivity to light, and blurring or double vision.

CLINICAL FEATURES

The characteristic symptoms of Graves’ eye disease feature the inflammation of the eye tissues. The eyes are painful, red and watery – particularly in sunshine or wind. The covering of the eye is inflamed and swollen. The lids and tissues around the eyes are swollen with fluid. The eyeballs bulge out of their sockets. Because of eye muscle swelling, the eyes are unable to move normally and there may be blurred or double vision. Some patients have decreased color vision as well.

• Red, swollen skin: people with Graves’ disease develop Graves’ dermopathy, which affects the skin, causing redness and swelling, often on the shins and feet
• Thyrotoxic crisis: this leads to a fever, a rapid pulse and even delirium

DIAGNOSTIC EVALUATION

• Radioactive iodine (RAI) uptake test: High in Graves’ disease and toxic nodular goiter, low in thyroiditis
• Serum T₄  and T₃: increased in hyperthyroidism. Normal T₄ with elevated T₃ indicates thyrotoxicosis
• Thyroid-stimulating hormone (TSH): Suppressed
• Thyroglobulin: increased
• TRH stimulation: hyperthyroidism is indicated if TSH fails to rise after administration of TRH
• Thyroid T₃ uptake: normal to high
• Protein-bound iodine: increased
• Serum glucose: elevated (related to adrenal involvement)
• Plasma cortisol: low levels (less adrenal reserve)
• Alkaline phosphatase and serum calcium: increased
• Liver function tests: abnormal
• Electrolytes: hyponatremia may reflect adrenal response or dilutional effect in fluid replacement therapy. Hypokalemia occurs because of GI losses and diuresis
• Serum catecholamines: decreased
• Urine creatinine: increased
• ECG: atrial fibrillations, shorter systole time, cardiomegaly, heart enlarged with fibrosis and necrosis
• Needle or open biopsy: may be done to determine cause hyperthyroidism, differentiate cysts or tumors, diagnose enlargement of thyroid gland
• Thyroid scan: differentiates between Graves’ disease and Plummer’s disease, both of which result in hyperthyroidism

Physiologic state – hyperthyroidism, untreated

Serum TSH               low

Serum free T₄           high

Serum T₃                   high

24-h radioiodine     high

Uptake

Physiologic state – hyperthyroidism, T₃ toxicosis

Serum TSH               low

Serum free T₄           normal  

Serum T₃                   high

24-h radioiodine     Normal or high

Uptake

Physiologic state – Primary hypothyroidism, untreated 

Serum TSH               low or normal

Serum free T₄           low

Serum T₃                   low or normal

24-h radioiodine     low or normal 

Uptake

Physiologic state – Hypothyroidism, secondary to pituitary disease 

Serum TSH               low or normal

Serum free T₄           low

Serum T₃                   low or normal

24-h radioiodine     low or normal 

Uptake

Physiologic state – Euthyroid, on exogenous thyroid hormone 

Serum TSH               normal

Serum free T₄           normal on T₄, low on T₃

Serum T₃                   high on T_3, normal on T₄

24-h radioiodine     low

Uptake

MANAGEMENT

Beta blockers

Beta blockers offer prompt relief of the adrenergic symptoms of hyperthyroidism such as tremor, palpitations, heat intolerance, and nervousness. Propranolol has been used most widely, but other beta blockers can be used. Nonselective beta blockers such as propranolol are preferred because they have a more direct effect on hypermetabolism. Therapy with propranolol should be initiated at 10 to 20 mg every six hours. The dose should be increased progressively until symptoms are controlled. Calcium channel blockers such as diltiazem can be used to reduce heart rate in patiens who cannot tolerate beta blockers

Iodides

Iodides block the peripheral conversion of thyroxine (T₄) to triiodothyronine (T₃) and inhibit hormone release. Iodides also are used as adjunctive therapy before emergency nonthyroid surgery, if beta blockers are unable to control the hyperthyroidism, and to reduce gland vascularity before surgery for Graves’ disease. Iodides are not used in the routine treatment of hyperthyroidism because of paradoxical increases in hormone release that can occur with prolonged use. Organic iodide radiographic contrast agents (e.g. iopanoic acid or ipodate sodium) are used more commonly than the inorganic iodides (e.g. potassium iodide). The dosage of either agent is 1 g per day for up to 12 weeks.

Antithyroid Drugs

Antithyroid drugs act principally by interfering with the organification of iodine, thereby suppressing thyroid hormone levels. Methimazole and propylthiouracil are the two agents available which are commonly used.

Methimazole

Methimazole usually is the drug of choice in nonpregnant patients because of its lower cost, longer half-life, and lower incidence of hematologic side effects. The starting dosage is 15 to 30 mg per day, and it can give in conjunction with a beta blocker. The beta blockade can be tapered after four to eight weeks and the methimazole adjusted. Maintenance dosage of 5 to 10 mg per day

Propyithiouracil

PTU is preferred for pregnant women because methimazole has been associated with rare congenital abnormalities. The starting dosage of PTU is 100 mg three times per day with a maintenance dosage of 100 to 200 mg daily

Radioactive Iodine

Radioactive iodine is the treatment of choice for most patients with Graves’ disease and toxic nodular goiter. It is inexpensive, highly effective, easy to administer, and safe. There has been reluctance to use radioactive iodine in women of childbearing years because of the theoretical risk of cancer of the thyroid, leukemia, or genetic damage in future offspring

Potential side effects from treatments for hypothyroidism

Treatment and Side Effects

Radioactive iodine – underactive thyroid (hypothyroidism) requiring lifelong thyroid hormone replacement

Most people who are treated with radioactive iodine will eventually develop hypothyroidism

Transiently sore thyroid gland

Anti-thyroid pills – rash, usually requiring stopping the drug (one in twenty risk)

Agranulocytosis: low white blood cells leading to infection risk (one in five hundred risks)

Surgery – underactive thyroid (hypothyroidism) requiring lifelong thyroid hormone replacement

Damage to nerves controlling vocal chords

Damage to parathyroid glands (glands responsible for maintaining calcium in the blood)

Surgical risks (Typically less than 1% with experienced surgeons)

Thyroidectomy: removal of thyroid gland, it may be subtotal thyroidectomy, hemithyroidectomy or total thyroidectomy

NURSING MANAGEMENT

1. Decrease cardiac output related to uncontrolled hyperthyroidism and hypermetabolic state

Interventions

• Monitor BP lying, sitting, and standing, if able. Note widened pulse pressure
• Monitor central venous pressure (CVP), if available
• Investigate reports of chest pain or angina
• Assess pulse and heart rate while patient is sleeping
• Monitor ECG, noting rate and rhythm. Document dysrhythmias
• Auscultate heart sounds, note extra heart sounds, development of gallops and systolic murmurs
• Monitor temperature, provide cool environment, limit bed linens or clothes, administer tepid sponge baths
• Observe signs and symptoms of severe thirst, dry mucous membranes, weak or thready pulse, poor capillary refill, decreased urinary output, and hypotension
• Weigh daily. Encourage chair-rest or bedrest. Limit unnecessary activities

• Fatigueness related to hypermetabolic state or altered body chemistry

Intervention

• Monitor vital signs, noting pulse rate at rest and when active
• Note development of tachypnea, dyspnea, pallor, and cyanosis
• Encourage patient to restrict activity and rest in bed as much as possible
• Provide for quiet environment, cool room, decreased sensory stimuli, soothing colors, quiet music
• Encourage patient to restrict activity and rest in bed as much as possible
• Provide comfort measures: touch therapy or massage, cool showers. Patient with dyspnea will be most comfortable sitting in high Fowler’s position
• Provide for diversional activities that are calming, e.g. reading, radio, television
• Avoid topics that irritate or upset patient. Discuss ways to respond to these feelings

• Disturbed thought processes related to altered sleep pattern

Intervention

• Assess thinking process. Determine attention span, orientation to place, person, or time.
• Note changes in behavior
• Assess level of anxiety
• Reorient to person, place, or time as indicated
• Provide quiet environment; decreased stimuli, cool room, dim lights
• Reorient to person, place, or time as indicated
• Provide, calendar, room with outside window, alter level of lighting to simulate day or night
• Present reality concisely and briefly without challenging illogical thinking
• Administer medication as indicated: sedatives, antianxiety agents, antipsychotic drugs
• Provide safety measures. Pad side rails, close supervision, applying soft restraints as last resorts as necessary

• Risk for imbalanced nutrition: less than body requirements related to nausea, vomiting, diarrhea

Intervention

• Monitor daily food intake. Weigh daily and report losses
• Encourage patient to eat and increase number of meals and snacks. Give or suggest high-calorie foods that are easily digested
• Provide a balance diet, with six meals per day
• Avoid foods that increase peristalsis and fluids that cause diarrhea
• Administer medications as indicated: glucose, vitamin B complex, insulin
• Consult with dietitian to provide diet high in calories, protein, carbohydrate and vitamins

• Anxiety related to CNS stimulation (hypermetabolic state)

Intervention

• Observe behavior indicative of level of anxiety
• Monitor physical responses, noting palpitations, repetitive movements, hyperventilation, and insomnia
• Stay with patient, maintaining calm manner. Acknowledge fear and allow patient’s behavior to belong to patient
• Describe and explain procedures, surrounding environment, or sounds that may be heard by patient
• Speak in brief statements. Use simple words
• Discuss with patient reasons for emotional liability and psychotic reaction
• Reduce external stimuli: place in quiet room, provide soft, soothing music; reduce bright lights, reduce number of persons contacting patient
• Reinforce expectation that emotional control should return as drug therapy progresses
• Administer antianxiety agents or sedatives and monitor effects

• Impaired tissue integrity related to alternation in protective mechanism of eye

Intervention

• Encourage use of dark glasses when awake and taping the eyelids shut during sleep as needed. Suggest use of sunglasses or eye patch. Moisten conjunctiva often with isotonic eye drops
• Elevate the head of the bed and restrict salt intake if indicated
• Instruct patient in extraocular muscle exercises if appropriate
• Provide opportunity for patient to discuss feelings about altered appearance and measures to enhance self-image
• Administer medications as indicated: adrenocorticotropic hormone (ACTH), prednisone, methylcellulose drops

• Knowledge deficit regarding condition, prognosis, treatment, self-care and discharge needs

Intervention

• Provide information appropriate to individual situation
• Provide information about signs and symptoms of hypothyroidism and the need for continuing follow-up care
• Identify stressors and discuss precipitators to thyroid crises: personal or social and job concerns, infection, pregnancy
• Monitor CBC periodically
• Identify signs and symptoms requiring medical evaluation: fever, sore throat, and skin eruptions
• Discuss drug therapy, including need for adhering to regimen, and expected therapeutic and side effects
• Explain need to check with physician before taking other prescribed or OTC drugs
• Review need for nutritious diet and periodic review of nutrient needs. Tell patient to avoid caffeine, artificial preservatives
• Emphasize importance of planned rest periods

Other Possible Nursing Diagnosis

• Imbalanced nutrition less than body requirements related intake less than metabolic needs secondary to excessive metabolic rate
• Risk for injury related to tremors
• Risk for hyperthermia related to lack of metabolic compensatory mechanisms secondary to hyperthyroidism
• Activity intolerance related to fatigue, exhaustion secondary to excessive metabolic rate
• Diarrhea related to increased peristalsis secondary to excessive metabolic rate
• Impaired comfort related to heat intolerance and profuse diaphoresis