Primary adrenal insufficiency (AI) is an endocrine disorder in which
hormones of the adrenal cortex are produced to an insufficient extent. Since receptors for adrenal
steroids have a wide distribution, initial symptoms may be nonspecific. In particular, the lack of
glucocorticoids can quickly lead to a life-threatening adrenal crisis. Therefore, current guidelines suggest applying a low threshold for testing and to rule out AI not before serum
cortisol concentrations are higher than 500 nmol/l (18 μg/dl). To ease the diagnostic, determination of morning
cortisol concentrations is increasingly used for making a diagnosis whereby values of>350 nmol/l are considered to safely rule out
Addison's disease. Also, elevated
corticotropin concentrations (>300 pg/ml) are indicative of primary AI when
cortisol levels are below 140 nmol/l (5 μg/dl). However, approximately 10 percent of our patients with the final diagnosis of
primary adrenal insufficiency would clearly have been missed for they presented with normal
cortisol concentrations. Here, we present five such cases to support the view that normal to high basal concentrations of
cortisol in the presence of clearly elevated
corticotropin are indicative of
primary adrenal insufficiency when the case history is suggestive of
Addison's disease. In all cases, treatment with
hydrocortisone had been started, after which the symptoms improved. Moreover,
autoantibodies to the adrenal cortex had been present and all patients underwent a structured national education program to ensure that self-monitored dose adjustments could be made as needed.