I have no pituitary gland . i have for many years been on 20mg a day of hydrocortisone. my cortisol levels are normally at 0.8 on lab reports and ive stable on this dosage for many yrs. how much should and would my stress dose increase my reading?

I am not certain what you mean by stress dose. ffI you mean you get stress from outside would affect level as the stress loop no longer controls your cortisol levels. I you mean an increase in dose when you undergo stress such as breaking a leg then your blood cortisol should go up. That assumes that the "cortisol" stress dose is the kind that a blood or salivary cortisol measures. Dex will not.