Addison's Disease

Addison's disease is a progressive, chronic disease process resulting from a decline in the production of adrenocortical steroids as the adrenal cortex is destroyed.

Causes and Incidence 

Most cases are the result of idiopathic atrophy of the adrenal cortex; the rest are due to destruction of the entire gland. Clinical signs often are manifested during periods of metabolic stress. About 4 in 100,000 individuals, across all age groups, are affected.

Disease Process 

A decline in cortisol and corticosterone production by the adrenal cortex results in multiple disturbances in fat, protein, and carbohydrate metabolism, which in turn give rise to diminished production of liver glycogen and increased production of insulin. This leads to hypoglycemia and muscle weakness. Electrolyte imbalances and dehydration are caused by an increase in sodium (Na) secretion and a decrease in potassium (K) secretion, leading to low serum concentrations of sodium and chloride and high serum concentrations of potassium. The decrease in cortisol also leads to an increase in adrenocorticotropic hormone (ACTH) and beta-lipotropin, which stimulates melanin production and causes hyperpigmentation. Over time, resistance to infection and stress diminishes. Dehydration may lead to reduced cardiac output and, ultimately, circulatory collapse.
 

Symptoms 

Early
Weakness, fatigue, orthostatic 

hypotension, tanning, freckles, vitiligo, darkened mucosal areas

Midcourse  
Nausea, vomiting, diarrhea, abdominal pain, headaches, dizziness, fainting, intolerance to cold

Late  
Weight loss, dehydration, hypotension, confusion, restlessness, emotional lability, small heart size
 

Potential Complications 

Acute stress or trauma in which the body's store of glucocorticoids is exhausted may trigger an adrenal crisis, which is characterized by generalized muscular debility; severe abdominal, back, and leg cramps; peripheral vascular collapse; and acute renal failure.
 

Diagnostic Tests 

ACTH stimulation test
No increase in cortisol

Blood chemistry  
Elevated potassium and blood  urea nitrogen (BUN); decreased sodium, bicarbonate, and fasting glucose

Complete blood count 
Na:K ratio less than 30:1; elevated hematocrit, eosinophils, and lymphocytes; decreased WBCs

Radiology 
Small heart; small adrenal size, calcifications; renal or pulmonary tuberculosis
 

Treatments 

Surgery
None

Drugs       
IV hydrocortisone, sodium chloride replacement; vasopressors to elevate blood pressure; hydrocortisone/fludrocortisone PO maintenance for life; antibiotics with evidence of infection; antitubercular drugs with evidence of tuberculosis

General      
Fluid replacement IV and PO; high-calorie diet; cardiac monitoring for peaked T waves; rest; monitoring for signs of infection; monitoring of urine output; instruction about the disease and maintenance medications.