If you cortisol and ACTH is low what does this mean?

You have... incomplete testing if that is all you have.

You likely have Addison's disease though. Low cortisol is usually Addison's but they should determine if the source is pituitary or adrenal. Using imaging is iffy (my adrenal scans were normal, my adrenals when removed were huge and my pit scans showed one tumor, when I had two, just to give you my story) and testing has to be done correctly - lab error is an issue with ACTH, and there are antibody tests to do as well. Was that done?

A stimulation test should be done to see if the adrenals are working too. The ACTH can indicate the source to a degree. If you are tan, that can indicate the adrenals are at fault and the pit is working.

Make sure you educate yourself on steroids - how to take them correctly, as well as salt dosing (a body without functioning adrenals cannot manage salt, and that usually causes the crisis), if you need other meds (not heard of E being necessary to be honest) and if you need other hormones such as DHEA or florinef to feel better. I take salt tablets to keep my BP up - so depending on your BP, you may or may not need extra salt dosing.

I had my adrenals removed - and few docs are good at the steroid thing - I suggest not taking prednisone and taking hydrocortisone for fewer side effects.

Low levels of ACTH and cortisol could mean a problem with the pituitary gland. The pituitary gland is a small gland located beneath the brain. The pituitary gland produces substances (hormones) that enter the bloodstream and help control many processes of the body. Hormones produced in the pituitary gland help manage these body functions: Growth. Blood pressure. Some aspects of pregnancy. Breast milk production. Sex organ functions in both women and men. Thyroid gland function. The conversion of food into energy (metabolism). Water balance in the body. sources : Webmd