The cortisol-to-DHEA-S ratio is being studied as an aging-related marker. It is not a direct measurement of remaining lifespan or a reason, by itself, to change hormone levels.

Understanding the research starts with the two measurements and the conditions in which they were collected.

Two hormones with different patterns

Cortisol is an adrenal hormone involved in the stress response, metabolism and other functions. Its level changes through the day. Clinical cortisol testing is used to investigate conditions involving too much or too little cortisol, with the sample type and collection timing chosen for that question.[1]

DHEA-S is another hormone made mainly by the adrenal glands. Its level changes with age and is interpreted with age, sex, symptoms and other findings. Clinical uses include investigating certain adrenal and reproductive-hormone disorders.[2]

Putting the two values into a ratio does not remove these differences in timing and interpretation.

What the aging study examined

A study used data from 969 adults to compare cortisol, DHEA-S and their ratio with several DNA-based estimates of aging. Age, sex and other demographic factors influenced the hormone measurements. Associations differed across the aging clocks; the ratio was not related to every measure in the same way.[3]

This was a study of associations between measurements. It did not test whether treating a ratio improved health or extended life. Its findings support further research into stress and aging, rather than establishing a treatment target.[3]

Why the original results still matter

If a report includes a ratio, the underlying cortisol and DHEA-S values remain important. The units, sample type, collection time and laboratory reference information are needed to understand what was calculated.

Cortisol results can be affected by medicines, exercise, stress and other factors. DHEA-S interpretation also depends on the person's circumstances. An unexpected result may lead to a more specific evaluation rather than a general conclusion about being “biologically older.”[1][2]