43 yro f tested high for cortisol in afternoon 28 ug/dl After suppression test am cortisol 3.7 and ACTH 2.0 CT showed adrenals normal. Ideas?

Cushing's diagnosis. Presumably you have symptoms (weight gain, skin changes, diabetes, etc). Sounds like you had screening tests (?overnight dex) but these tests do not establish the diagnosis. False positives occur with depression, obesity, alcohol consumption. You really need to see an Endocrinologist to get this worked up. If it is Cushing's, 70% is in the pituitary, not the adrenal.