Laboratory Monitoring for Adrenal Insufficiency

Initial Diagnostic Laboratory Panel

Morning serum cortisol and plasma ACTH measurements distinguish primary from secondary adrenal insufficiency and establish baseline values, according to the Journal of Clinical Oncology 1
Basic metabolic panel assessment reveals hyponatremia in 90% of newly diagnosed cases and hyperkalemia in ~50% of primary adrenal insufficiency cases, as reported by the Journal of Clinical Oncology 1

The ACTH stimulation test, which involves administering 0.25 mg cosyntropin intramuscularly or intravenously and measuring serum cortisol at 30 and/or 60 minutes post-administration, is used to confirm adrenal insufficiency, as recommended by Praxis Medical Insights 2
A peak cortisol level <500 nmol/L (18 μg/dL) is diagnostic of adrenal insufficiency, according to Praxis Medical Insights 2

21-hydroxylase (anti-adrenal) autoantibodies identify autoimmune etiology, the most common cause of primary adrenal insufficiency, as reported by Praxis Medical Insights 2
Adrenal CT imaging evaluates for metastasis, hemorrhage, tumor, or infection if autoantibodies are negative, as recommended by the Journal of Clinical Oncology 1

Serum electrolytes (sodium, potassium) are monitored regularly to assess mineralocorticoid replacement adequacy in primary adrenal insufficiency and detect over-replacement, according to the Journal of Clinical Oncology 1
Morning cortisol levels are measured periodically to assess if replacement dosing is appropriate, though interpretation is complex in patients on exogenous steroids, as reported by the Journal of Clinical Oncology 4

Never delay treatment of suspected acute adrenal crisis to obtain diagnostic tests, as adrenal crisis is life-threatening and requires immediate IV hydrocortisone and fluid resuscitation, as recommended by Praxis Medical Insights 2
Laboratory confirmation of adrenal insufficiency should not be attempted in patients on high-dose corticosteroids for other conditions until treatment is ready to be discontinued, as results will be uninterpretable, according to the Journal of Clinical Oncology 4

For patients on immune checkpoint inhibitors, glucose is monitored at baseline and with each treatment cycle while on therapy and at follow-up visits for at least 6 months to detect checkpoint inhibitor-associated diabetes mellitus, as recommended by the Journal of Clinical Oncology 5
Before surgery or procedures, endocrine consultation is ensured for stress-dose planning and adequate cortisol coverage is verified, as recommended by Praxis Medical Insights 2