Updated Diagnostic Cortisol Values for Adrenal Insufficiency

Inclusion Criteria for healthy volunteers:

Male and female outpatients 18 years or older without prior diagnosis of primary or central adrenal insufficiency.

Inclusion Criteria for patients with known adrenal insufficiency:

Males and females 18 years or older with established diagnosis of primary or central adrenal insufficiency as previously documented in the electronic medical record by a failed CST (peak cortisol level \< 18 μg/dL) or morning serum cortisol \< 3 mcg/dL with an appropriate clinical circumstance (e.g. Sheehan's syndrome, pituitary surgery and/or irradiation, bilateral adrenalectomy, etc) that strongly supports a true diagnosis of primary or central adrenal insufficiency, and current use of physiologic, replacement dose glucocorticoids. Inpatients with non-critical illness and outpatients are eligible.

Inclusion Criteria for patients with suspected adrenal insufficiency:

Males and females 18 years or older with suspected diagnosis of primary or central adrenal insufficiency by any cause based on clinical evaluation by a study team member. Inpatients with non-critical illness and outpatients are eligible.

Exclusion Criteria for all groups:

1. Moderate to severe liver impairment or abnormal albumin or cortisol binding globulin concentrations
2. Renal impairment with eGFR \< 60 mL/min/1.73m2 and/or diagnosis of nephrotic syndrome
3. Pregnancy or nursing mothers
4. Use of estrogen preparations
5. Major depressive disorder, severe malnutrition, anorexia, chronic fatigue syndrome (disorders that alter HPA axis function)
6. Use of any medications that induce hepatic cytochrome P-450 enzymes, e.g., barbiturates, phenytoin, rifampin, amino-glutethimide and mitotane
7. Active medical treatment of Cushing's syndrome (status-post surgical treatment is acceptable)
8. Uncontrolled hypo- or hyperthyroidism
9. Use of biotin within the past 72 hours
10. Regular alcohol and/or cannabis use
11. Be assessed by the investigators as unsuitable for participation in this study for any reason.

Additional Exclusion Criteria for healthy volunteers only:
12. Regular use of any oral glucocorticoid (e.g. hydrocortisone, prednisone, dexamethasone) within 6 weeks of the screening visit
13. Use of oral or nasal steroid (glucocorticoid) inhalers in the past 2 weeks
14. Regular use of any steroid creams, gels, ointments, or lotions
15. Use of steroid (glucocorticoid) injections in the past 6 months
16. Regular use of opioids
17. Regular use of suboxone
18. Regular use of megestrol acetate