Addison's Disease: Etiology and Pathophysiology

Etiology and Pathophysiology

• Adrenocortical insufficiency indicates Addison's disease if primary.
• Adrenocortical insufficiency results from a lack of pituitary ACTH if secondary.
• The common cause is an autoimmune response to adrenal tissue.
• Susceptibility genes are beginning to be identified for Addison's disease.
• Other endocrine conditions are often found to coincide with Addison's disease.
• Most often ocurrs in adults younger than 60 years old
• Affects both genders equally
• It’s more common in white females if it stems from an autoimmune response.
• It does not become evident until 90% of the adrenal cortex is destroyed.
• The disease is usually advanced before diagnosis.
• All three classes of adrenal corticosteroids are decreased in Addison's disease, including Glucocorticoids, Mineralocorticoids, and Androgens.

Clinical Manifestations

• Primary features include progressive weakness, fatigue, weight loss, anorexia, and skin hyperpigmentation
• Other clinical manifestations include orthostatic hypotension, hyponatremia, hyperkalemia, nausea and vomiting, diarrhea, irritability and depression.

Complications

• Risk for life-threatening Addisonian crisis is caused by insufficient adrenocortical hormones.
• Addisonian crisis can be triggered by stress, withdrawal of hormone replacement, after adrenal surgery, or following sudden pituitary gland destruction.
• Addison’s can lead to hypotension, tachycardia, dehydration, hyponatremia, hyperkalemia, hypoglycemia, fever, weakness and confusion.
• Hypotension can lead to shock.
• Circulatory collapse is often unresponsive to usual treatment.
• GI manifestations include severe vomiting, diarrhea, and abdominal pain.
• Pain in lower back or legs can occur due to potassium irregularities.

Diagnostic Studies

• Subnormal levels of cortisol indicate Addison's disease.
• Levels fail to rise over basal levels with ACTH stimulation test which indicates primary adrenal disease, or else a positive response to ACTH stimulation indicates functioning adrenal gland.
• Abnormal laboratory findings include hyperkalemia, hypochloremia, hyponatremia, hypoglycemia, anemia, increased BUN, and low urine cortisol levels.
• Other abnormal findings include ECG, low voltage, vertical QRS axis, peaked T waves from hyperkalemia.
• CT and MRI used to localize tumors.
• It is important to identify adrenal calcifications or enlargement.

Collaborative Care

• Hydrocortisone is the therapy used most commonly as replacement
• Glucocorticoid dosage must be increased during times of stress to prevent Addisonian crisis.
• Addisonian crisis treatment is directed at shock management and high-dose hydrocortisone replacement.

Nursing Implementation

• Acute intervention requires frequent assessment, assessing vital signs and signs of fluid and electrolyte imbalance every 30 minutes to 4 hours for first 24 hours.
• Take daily weights., administer corticosteroid therapy diligently, protect against infection, assist with daily hygiene, and protect from extremes like light, noise and temperature.
• Ambulatory and home care requires that glucocorticoids usually given in divided doses and mineralocorticoids are given once in the morning.
• The one-time dose of mineralocorticoids reflects normal circadian rhythm, and decreases side effects of corticosteroids.
• Long-term care includes need for extra medication and stress management.
• Situations requiring corticosteroid adjustment include fever, influenza, tooth extraction and physical exertion.
• Doses are doubled for minor stressors and tripled for major stressors.
• Expected effects of corticosteroid therapy include, anti-inflammatory action, immunosuppression, maintenance of normal BP, carbohydrate and protein metabolism.
• Take the medication in the morning with food to reduce gastric irritation, but the medication must not be stopped abruptly.
• Assess for corticosteroid-induced osteoporosis.

Student Response Question

• The nurse determines that the patient in acute adrenal insufficiency is responding favorably to treatment when:
  • The patient appears alert and oriented.
  • The patient's urinary output has increased.
  • Pulmonary edema is reduced as evidenced by clear lung sounds.
  • Laboratory tests reveal elevations of potassium and glucose serum levels and a decrease in the sodium level.