(ad′ĭ-sŏn)

[Thomas Addison, Brit. physician, 1793-1860]
A rare illness marked by gradual, progressive failure of the adrenal glands and by insufficient production of steroid hormones. Patients with Addison's disease are deficient both in glucocorticoids, e.g., cortisol, and in mineralocorticoids, e.g., aldosterone. Cortisol is important to glucose metabolism; it affects the metabolism of proteins, carbohydrates and fats, and helps maintain blood pressure and cardiovascular function. Hypovolemia and hypotension may result from aldosterone deficiency.
SEE: primary adrenal insufficiency

CAUSES
Primary adrenal failure typically results from autoimmune destruction of the adrenal glands (80% of cases), chronic infections; e.g., tuberculosis, cytomegalovirus, and other viral diseases such as Lyme disease or histoplasmosis; or cancers that metastasize to the adrenal glands from other organs, such as cancers of the lungs or breast. Secondary adrenal insufficiency is related to suppression of hypothalamic-pituitary-adrenal axis function.

SYMPTOMS AND SIGNS
The patient may be symptom-free until the majority of adrenal tissue is destroyed. Early complaints are usually nonspecific, e.g., a feeling of weakness or fatigue. Subsequently patients may notice a lack of appetite, weight loss, nausea, vomiting, abdominal pain, a craving for salt, and dizziness. Physical findings may include postural hypotension and increased skin pigmentation.

DIAGNOSIS
Serum chemistries usually reveal hyponatremia and hyperkalemia (a low concentration of serum sodium and a high concentration of potassium). If these findings are present, a cosyntropin stimulation test may be performed to establish the diagnosis. Fasting plasma cortisol levels less than 10 μg/dL suggest adrenal insufficiency. Cortisol levels remain reduced even after the injection of synthetic adrenocorticotropic hormone (ACTH).

TREATMENT
Chronic adrenal insufficiency is managed with corticosteroids, e.g., hydrocortisone or prednisone, usually taken twice a day, at the lowest effective dose to replace cortisol. If the patient requires mineralocorticoid replacement, fludrocortisone is prescribed. Because of the vital role of cortisol in the body’s response to stress, the maintenance dose of these medications during episodic illnesses or stresses, e.g., surgeries, is increased and then tapered over several days back to baseline levels.
SEE: adrenal crisis

IMPACT ON HEALTH
Untreated patients may develop progressive problems with abdominal pain, nausea, vomiting, low blood pressure, electrolyte disturbances, or shock during major illnesses. Patients treated with corticosteroids have an excellent prognosis.

PATIENT CARE
Patients with primary adrenal insufficiency who are suffering from other acute conditions are assessed frequently for hypotension, tachycardia, fluid balance, and electrolyte and glucose levels. Prescribed adrenocortical steroids, with sodium and fluid replacement, are administered. The patient is protected from stressors, e.g., infection, noise, and light and temperature changes. Extra time for rest and relaxation is planned.

For chronic maintenance therapy: Both patient and family are taught about the need for lifelong replacement therapy and medical supervision. Patients are taught about self-administration of steroid therapy (typically two thirds of the dose is given in the a.m. and one third in the p.m. to mimic diurnal adrenal activity). Symptoms of overdose and underdose and the course of action, if either occurs, are explained. The patient and family also are taught how to monitor blood pressure, heart rate, and blood glucose level. A medical alert tag should be worn (or a card carried) indicating that the person has Addison's disease and requires a 100 mg cortisol injection if found severely injured or incapacitated. Patient and family should learn how to administer hydrocortisone by injection and should have a prepackaged syringe and needle with the drug readily available at all times. The patient also should be taught to recognize physical or mental stressors and how to adjust the usual dosage to prevent a crisis. He or she is instructed to increase fluid and salt replacement if perspiring and to follow a diet high in sodium, carbohydrates, and protein, with small, frequent meals if hypoglycemia or anorexia occurs. Measures to help prevent infection include getting adequate rest, avoiding fatigue, eating a balanced diet, and avoiding people with infections. Verbalization of feelings and concerns is encouraged. The patient is assisted in developing coping strategies and is referred for further mental health or stress management counseling if warranted. Educational materials and support are available from the National Adrenal Diseases Foundation http://www.nadf.us/ or the National Institutes of Health at http://endocrine.niddk.nih.gov/pubs/addison/addison.aspx.