From the Guidelines
Addison's disease diagnosis should be based on a combination of clinical evaluation, laboratory tests, and imaging studies, with the cosyntropin test being the gold standard for diagnosis, where a serum cortisol level exceeding 550 nmol L1 after 30 and/or 60 min is considered normal 1. The diagnostic process typically begins with blood tests to measure cortisol levels, often through an early morning (8 AM) serum cortisol test. If cortisol levels are low, an ACTH stimulation test is performed using cosyntropin (0.25 mg intramuscularly or intravenously), with measurements of serum cortisol after 30 and/or 60 min 1. Some key points to consider in the diagnostic workup of Addison's disease include:
- Measuring ACTH levels to differentiate between primary and secondary adrenal insufficiency
- Assessing for autoimmune causes through adrenal antibodies
- Evaluating electrolyte levels for hyponatremia and hyperkalemia
- Considering comprehensive metabolic panels, complete blood counts, and renin-aldosterone testing
- Using imaging studies such as CT scans or MRIs of the adrenal glands to identify structural abnormalities or diseases affecting the adrenals It is crucial to note that if there is a clinical suspicion of impending acute adrenal crisis, treatment with intravenous hydrocortisone and physiologic saline infusion should not be delayed, and blood samples for cortisol and ACTH measurement should be secured prior to treatment if possible 1.
From the FDA Drug Label
COSYNTROPIN for injection is an adrenocorticotropin hormone indicated, in combination with other diagnostic tests, for use as a diagnostic agent in the screening of adrenocortical insufficiency in adults and pediatric patients. Obtain blood samples for serum cortisol level at baseline and exactly 30 and 60 minutes after cosyntropin for injection administration. Diagnostic Inaccuracies: Cortisol levels and subsequent diagnosis of adrenocortical insufficiency following cosyntropin for injection administration may be inaccurate if patients are on certain medications because of their effect on cortisol or cortisol binding globulin levels
The diagnostic criteria for Addison's disease (Adrenal Insufficiency) involve:
- Cosyntropin stimulation test: administering cosyntropin and measuring serum cortisol levels at baseline, 30 minutes, and 60 minutes after administration.
- Interpretation of cortisol levels: the test results are used to diagnose adrenocortical insufficiency, but may be affected by certain medications.
- Medication considerations: stopping glucocorticoids, spironolactone, and estrogen-containing drugs before testing to ensure accurate results 2
From the Research
Diagnostic Criteria for Addison's Disease
The diagnostic criteria for Addison's disease, also known as adrenal insufficiency, can be identified through a combination of clinical presentation, laboratory tests, and physical examination findings. The key diagnostic features include:
- History of symptoms such as salt craving, orthostatic hypotension, and gastrointestinal complaints 3
- Physical examination findings of increased pigmentation and small or unidentifiable adrenal glands 3
- Laboratory tests, including:
- Electrolyte imbalance disorders, such as hyponatremia 4
- Hyperpigmentation of the skin and mucosal surfaces 4, 5
Laboratory Tests
Laboratory tests play a crucial role in diagnosing Addison's disease. The tests include:
- Serum cortisol concentrations: Low levels of cortisol can indicate adrenal insufficiency 4, 5, 6
- ACTH stimulation test: This test measures the response of the adrenal glands to ACTH stimulation 5, 6
- 21-hydroxylase antibodies: The presence of these antibodies can indicate autoimmune Addison's disease 3
- Electrolyte testing: Abnormal electrolyte levels, such as hyponatremia, can be a sign of adrenal insufficiency 4
Clinical Presentation
The clinical presentation of Addison's disease can vary, but common symptoms include: