What sort of disease is a corticosteroid imbalance?

Not a diagnosis. But there can be excess or deficiency of cortisol in the body and both of these conditions come with specific signs and symptoms and just to clarify there is no such thing as " adrenal fatigue".
What do you mean? Corticosteroid imbalance is not a medical term. Do you mean cortisol excess ( cushings) or deficiency (addison's) or the made-up "adrenal fatigue"?