Adrenal insufficiency

Addison disease also known as adrenal insufficiency refers to inadequate secretion of corticosteroids from partial or complete destruction of adrenal glands. 

Pathology

Addison disease has a number of causes:¹

• idiopathic autoimmune disorders which is the most common cause (80% of cases) in developed countries¹
• granulomatous disease: tuberculosis (is the most common infectious cause in underdeveloped countries), sarcoidosis
• neoplasms: metastases (e.g. lung, ovary, kidney, melanoma), lymphoma, leukemia
• adrenal hemorrhage: shock, sepsis (Waterhouse-Friderichsen syndrome ), coagulation disorders, antiphospholipid syndrome
• systemic fungal infection: histoplasmosis (most common infection in southeastern and south central USAUnited States)¹

The disease course may be either acute, subacute, or chronic ²

• acute: occurs within a few weeks to months and is caused by bilateral adrenal hemorrhage (adrenal apoplexy) or secondary to shock and sepsis or trauma (Addisonian crises)
• subacute disease (adrenalitis): when the disease has been present for less than 2 years
• chronic: secondary to chronic autoimmune disorder or chronic granulomatous infection (tuberculosis), the adrenal glands become atrophic and calcified

Clinical presentation

Depends on the course of the disease

• acute stage: the patient presents with fever, back pain, hypotension, weakness
• chronic stage: progressive lethargy, weakness, cutaneous pigmentation, weight loss

Laboratory data

• chemistry: hyponatremia, hyperkalemia, azotemia, hypercalcemia, hypoglycemia
• Adrenocorticotrophicadrenocorticotrophic hormone (ACTH) stimulation test: cortisol level fail to fall

Radiographic features

 General

• Addison is bilateral disease
• cannot diagnose Addison disease by imaging alone
• CT is the best imaging modality 

CT

Imaging features depend on the cause and the course of the disease either acute, subacute or chronic

• acute: bilateral adrenal hematomas are demonstrated. 
• subacute (adrenalitis): enlargement of both adrenal glands, with necrotic centers and peripheral enhancing rim
• chronic: both adrenal glands appear small and atrophic associated with calcifications (adrenal calcification) in granulomatous adrenalitis 

Treatment and prognosis

• acute: glucocorticoid therapy, volume and electrolytes replacement and correct etiology
• chronic: glucocorticoid and mineralocorticoid replacement

Differential diagnosis

• adrenal metastasis and lymphoma
• adrenal hemorrhage
• adrenal TBtuberculosis
• adrenal adenoma