What would cause normal levels of cortisol but "undetectable" levels of dhea?

Steroidogenesis: Hi. Cortisol is a tightly regulated end product steroid hormone produced in the adrenals, whereas DHEA is an intermediate in the steroidogenic pathways in steroidogenic tissues (adrenal cortex, ovaries, testes), and not a regulated end product steroid. As long as you have enough cortisol, you're good. By your age (53), you're menopausal, and your ovarian DHEA is very low (~zero).