The adrenal anti-stress, immunity, and longevity hormone. The production level will decrease with stress and age, and it is required for proper immune function, especially as it is related to the thymus gland. The level is low or zero in most cancer patients, and declines with aging. The DHEA-S form of the hormone is a better analyte to test than DHEA itself because of its longer half-life (presence in the blood) and more abundance. However, the two are readily inter converted. DHEA (DHEA-S) is exerting its affect through the blood therefore other specimens, e.g. saliva may not give proper results.