Adrenal insufficiency

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

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
• adrenocorticotrophic hormone (ACTH) stimulation test: cortisol level fail to fall

Pathology

Addison disease has a number of causes ¹:

• idiopathic autoimmune disorders which are the most common cause (80% of cases) in developed countries ¹
• granulomatous disease: tuberculosis (is the most common infectious cause in underdeveloped countries) and sarcoidosis
• neoplasms: metastases (e.g. lung, ovary, kidney, melanoma), lymphoma, and leukaemia
• adrenal haemorrhage: shock, sepsis (Waterhouse-Friderichsen syndrome), coagulation disorders, antiphospholipid syndrome
• systemic fungal infection: histoplasmosis (most common infection in the southeastern and south central United 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 haemorrhage (adrenal apoplexy) or secondary to shock and sepsis or trauma (Addisonian crises)
• subacute disease (adrenalitis): when the disease has been present for less than 2two years
• chronic: secondary to chronic autoimmune disorder or chronic granulomatous infection (tuberculosis), the adrenal glands become atrophic and calcified

Radiographic features

Addison is bilateral disease that cannot be diagnosed by imaging alone. CT is the best imaging modality for the adrenal assessment in this clinical scenario. 

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 centres 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 aetiology
• chronic: glucocorticoid and mineralocorticoid replacement

Differential diagnosis

• adrenal metastasis and lymphoma
• adrenal hemorrhage
• adrenal tuberculosis
• adrenal adenoma