Laboratory findings
Electrolyte abnormalities — Hyponatremia is found in 70 to 80 percent of patients, reflecting both sodium loss and volume depletion caused by mineralocorticoid deficiency and increased vasopressin secretion caused by cortisol deficiency. (See .)
Hyperkalemia often associated with a mild hyperchloremic acidosis occurs in up to 40 percent of patients due to mineralocorticoid deficiency.
Hypercalcemia is a rare occurrence that may be associated with acute renal insufficiency []. (See .)
Hypoglycemia — Hypoglycemia may occur after prolonged fasting or, rarely, several hours after a high-carbohydrate meal []. It is rare in adults in the absence of infection, fever, or alcohol ingestion. Hypoglycemia is most common in infants and children with primary adrenal insufficiency, patients with secondary adrenal insufficiency caused by isolated ACTH deficiency [], and patients with type 1 diabetes mellitus who develop adrenal insufficiency. In those with both type 1 diabetes and primary adrenal insufficiency, sensitivity to their exogenous insulin is increased because of loss of the gluconeogenic effect of cortisol and the hyperglycemic effects of epinephrine []. (See .)
Hematologic findings — Normocytic anemia is seen in up to 15 percent of patients [], although patients with polyglandular autoimmune syndrome types 1 and 2 may have coexisting pernicious anemia (see ). Relative eosinophilia was reported to be a marker of adrenal insufficiency by George Thorn in 1948 []. Small subsequent series suggest that the eosinophil count is greater than 500/mm3 in less than 20 percent of patients []. Thus, while the presence of eosinophilia may suggest adrenal insufficiency, it does not have a high sensitivity, and when found incidentally, other causes such as allergy or infection should be investigated [].
One study found that the combination of a history of glucocorticoid withdrawal, nausea, hyperkalemia, and eosinophilia was a useful predictor of adrenal insufficiency in an inpatient population [].
Uptodate.