Hypercalcemia
Hypoglycemia
Hyponatremia
Hyperkalemia
Metabolic acidosis
Low stimulation of the renal distal tubule by aldosterone = sodium wasting in the urine and H+ retention
Low stimulation of the renal distal tubule by aldosterone = sodium wasting in the urine and H+ retention
Chemistry
Random cortisol, renin, and ACTH levels
Do not wait for levels before starting treatment
ACTH (cosyntropin) stimulation test
Do not wait for levels before starting treatment
Addison's disease
Corticosteroid withdrawal
Sheehan's syndrome
Secondary adrenal insufficiency - deficiency of ACTH 
Cushing's syndrome
Tertiary adrenal insufficiency - deficiency of CRH 
Wilson's disease
Zollinger-Ellison syndrome