Is progesterone in men connected to adrenal steroid pathways?

In men, circulating progesterone is a physiologically active hormone produced by both the adrenal cortex and testicular Leydig cells. Rather than functioning solely as a female reproductive hormone, it serves as a critical, mandatory intermediate in male steroidogenesis.

Biosynthetic pathways and molecular mechanisms

• Dual-source synthesis: Progesterone is synthesized from cholesterol via pregnenolone by the action of the enzyme 3β-hydroxysteroid dehydrogenase type 2 (HSD3B2) in both the adrenal glands and testicular Leydig cells, which secrete it directly into systemic circulation.
• Central steroidogenic branch point: Within the adrenal cortex, progesterone is an obligatory precursor. It is converted to 11-deoxycorticosterone to fuel mineralocorticoid (aldosterone) pathways and undergoes 17α-hydroxylation to enter the downstream glucocorticoid (cortisol) and adrenal androgen pathways.

Clinical and metabolic implications

• Enzymatic blockades: Because of its position as a central precursor, circulating progesterone levels are highly sensitive to downstream metabolic disruptions.
• Congenital adrenal hyperplasia (CAH): Genetic deficiencies in key steroidogenic enzymes cause characteristic progesterone accumulations. In 21-hydroxylase deficiency, the conversion of progesterone to deoxycorticosterone is impaired, leading to upstream accumulation. Similarly, 17α-hydroxylase/17,20-lyase deficiency prevents downstream conversion into cortisol and sex steroids, resulting in highly elevated serum progesterone alongside characteristically low cortisol and androgens.

Bottom line

• Progesterone in men is intrinsically connected to adrenal and gonadal pathways; consequently, deviations in circulating progesterone serve as a highly sensitive biomarker of altered steroidogenesis and disrupted downstream steroid hormone metabolism.