Cortasol test 3.90 with dexamethasone. is this a normal test result. i do have a 1.4cm tummer on left adrenal gland and 1cm on right?

Low dose dexamethasone suppression test is a screening test to diagnose Cushing Syndrome. The typical dose is 1mg or 3mg taken at 11pm-12am, and cortisol checked 8am the next morning. If the cortisol is still elevated (above 1.8mcg/dL), other labs should be checked, such as 24 hour urine free cortisol, ACTH level, and repeat suppression test with 8mg. Other adrenal hormones should also be checked

You do not tell us you were tested with low or high dose suppression test with dexamethasone. If you received only 1 mg on the previous night, the cortisol level the next morning should be less than 1.8 mcg/dL then so the result of 3.9 mcg/dL is abnormal and you probably have active adrenal adenoma(s).