I have very high levels of DHEA (480) but borderline low cortisol (3.7). Endocrinologist says PCOS. I worry about adrenal fatigue. Should I worry?

No. DHEA is not the correct measure. I'm assuming it's the DHEAS (adrenal form). would suggest evaluating for LOCAH (late onset congenital adrenal hyperplasia). The evaluation should include the 3B OH enzyme in the ACTH stimulation test, therefore both the 17 OH Progesterone and the pregnenolone need to be measured. Also a repeat of the cortisol would maybe reveal a higher number. Hope this helps.