Testosterone Production and Regulation

Testosterone is produced primarily in the Leydig cells of the testes (men) and in the ovaries and adrenal glands (women). Production is regulated by the hypothalamic-pituitary-gonadal (HPG) axis: the hypothalamus releases GnRH, stimulating the pituitary to release LH, which signals testosterone production. Testosterone feeds back to suppress GnRH and LH. Modern lifestyle factors including poor sleep, chronic stress, obesity, endocrine disruptors, and sedentary behavior can suppress the HPG axis, leading to lower testosterone production beyond normal age-related decline.

1

Lifestyle Matters More Than Age

While testosterone naturally declines with age, lifestyle factors (sleep, exercise, body composition, stress) have a larger impact than aging alone for most men under 60.

2

Test in the Morning

Testosterone peaks in the early morning and can drop 30-40% by afternoon. Always test between 7-10 AM fasting for accurate results.

Optimal Testosterone Benchmarks

Functional Range (Hormonal Focused) Men optimal: 500-900 ng/dL; Women optimal: 30-70 ng/dL
Standard Lab Range Men standard: 264-916 ng/dL; Women standard: 15-70 ng/dL

Common Questions

What causes low testosterone?

Common causes include poor sleep, obesity (especially visceral fat), chronic stress, excessive alcohol, sedentary lifestyle, endocrine disruptors, and certain medications. Age-related decline is natural but often accelerated by these factors.

Should I consider testosterone replacement therapy?

TRT should be considered after optimizing lifestyle factors and confirming persistently low levels. It requires ongoing medical supervision and has trade-offs including potential fertility effects and the need for lifelong treatment.