What is the diagnostic approach for an Addisonian crisis?

Diagnosing Addisonian Crisis

Addisonian crisis should be diagnosed immediately based on clinical presentation and laboratory findings, without delaying treatment for diagnostic procedures if the patient is clinically unstable. 1, 2

Clinical Presentation

• Common symptoms include malaise, fatigue, nausea, vomiting, abdominal pain, muscle pain/cramps, dehydration, hypotension, and shock 2
• Neurological manifestations may include impaired cognitive function, confusion, loss of consciousness, and coma 2
• Hyperpigmentation of skin is a classic sign of primary adrenal insufficiency due to elevated adrenocorticotropic hormone levels 3
• Symptoms can develop rapidly, progressing from relatively mild symptoms to life-threatening shock within hours 4

Laboratory Findings

• Characteristic laboratory abnormalities include hyponatremia, hyperkalemia, increased creatinine, hypoglycemia, and mild hypercalcemia 2, 5
• Hyponatremia is present in 90% of newly diagnosed adrenal insufficiency cases 5
• Hyperkalemia is present in only about 50% of cases, so its absence cannot rule out adrenal insufficiency 5

Diagnostic Approach

• If clinical suspicion of adrenal crisis exists, blood samples for cortisol and ACTH should be secured prior to treatment, but treatment should never be delayed for diagnostic procedures 1, 2
• Basal cortisol <250 nmol/L with elevated ACTH in acute illness is diagnostic of primary adrenal insufficiency 5
• Basal cortisol <400 nmol/L with elevated ACTH in acute illness raises strong suspicion of adrenal insufficiency 5

Confirmatory Testing

• The standard test for confirming adrenal insufficiency is the cosyntropin (synacthen) test 1, 5
• Administer 0.25 mg cosyntropin intramuscularly or intravenously 1, 5
• Measure serum cortisol at baseline, 30 minutes, and/or 60 minutes after administration 5
• A peak cortisol value should exceed 500-550 nmol/L to be considered normal 1, 5
• This test should only be performed after the patient has been stabilized if they presented in crisis 1, 5

Common Precipitating Factors

• Gastrointestinal illness with vomiting/diarrhea is a common trigger 2
• Other precipitating factors include infections, surgical procedures without adequate steroid coverage, physical injuries or trauma, myocardial infarction, and severe allergic reactions 2
• Abrupt termination of long-term glucocorticoid medication can precipitate an Addisonian crisis 6
• Certain medications like phenobarbital can accelerate metabolism of both exogenous and endogenous steroids, potentially triggering a crisis 7

Differential Diagnosis

• Adrenal insufficiency must be distinguished from syndrome of inappropriate antidiuretic hormone secretion (SIADH), as both can present with similar laboratory findings of euvolemic hypo-osmolar hyponatremia 5
• Sepsis can mimic Addisonian crisis with hypotension, lethargy, and fever 8
• Pituitary apoplexy can result in secondary Addisonian crisis and requires specific imaging for diagnosis 8

Important Considerations

• The use of exogenous steroids and inhaled steroids can affect test results 5
• In patients with known adrenal insufficiency who present with symptoms of crisis, diagnostic testing is not necessary before initiating treatment 2, 3
• Patients with Addison's disease may be at higher risk of adrenal crisis when receiving certain medications or treatments, such as bisphosphonates, which can provoke an acute phase reaction 9

Remember that Addisonian crisis is a life-threatening emergency requiring immediate treatment with intravenous hydrocortisone and fluid resuscitation, even before the diagnosis is confirmed 1, 2, 3.