Do low DHEA-S and low morning cortisol indicate reduced adrenal steroid output?

Clinical markers of adrenal output

• Biomarker dynamics: Low circulating DHEA-S directly reflects a reduction in the steroidogenic capacity of the adrenal cortex's zona reticularis, which declines to less than 20% of peak adult levels during normal age-related adrenopause.
• Adrenal insufficiency: While low DHEA-S is common in aging men, a concurrent drop in early morning serum cortisol (<3–5 µg/dL) is a critical marker of pathological hypothalamic-pituitary-adrenal (HPA) axis sluggishness or primary adrenal insufficiency, rather than benign aging.

Androgen pool contribution and intracrine mechanisms

• Circulating pool: In eugonadal men, the testes secrete 90% to 95% of circulating testosterone and DHT. Consequently, the peripheral conversion of adrenal precursors like DHEA-S contributes less than 5% to the actual circulating androgen pool under normal physiological conditions.
• Intracrine conversion: Although its systemic contribution is minimal, DHEA-S serves as a vital reservoir for local, intracrine synthesis inside peripheral target tissues (such as the prostate and skin). In aging men, this intracellular conversion provides 40% to 50% of the total body androgen pool, bypassing the bloodstream entirely.

Bottom line

• Key takeaway: Low DHEA-S and low morning cortisol are clear markers of reduced adrenal steroid output, though low cortisol specifically flags pathological adrenal impairment. DHEA-S does not meaningfully contribute to the circulating androgen pool in men, but it serves as a critical precursor for localized, intracrine androgen activity in target tissues.