What is secondary hypogonadism?

Secondary hypogonadism occurs when the pituitary gland or hypothalamus fails to produce adequate signaling hormones (luteinizing hormone and follicle-stimulating hormone) needed to stimulate testosterone production in the testes. The testes themselves remain functionally capable, but receive insufficient chemical direction to manufacture normal testosterone levels.

This differs from primary hypogonadism, where the testes themselves are diseased or damaged and cannot produce testosterone regardless of normal pituitary signaling. In secondary hypogonadism, blood tests typically show low testosterone paired with low or inappropriately normal luteinizing hormone levels, pointing to a brain-level cause rather than testicular failure.

Common causes include pituitary tumors, head injury, obesity, sleep disorders, chronic illness, certain medications, and aging. Some men develop secondary hypogonadism after prolonged anabolic steroid use, as the brain's signaling system becomes suppressed. Others have congenital conditions affecting hypothalamic development.

Secondary hypogonadism is medically significant because it can sometimes be reversed or improved by treating the underlying pituitary or hypothalamic problem, particularly if a tumor or medication is the culprit. For men seeking testosterone replacement therapy, identifying whether hypogonadism is secondary or primary helps determine whether restoration therapy, fertility-focused treatment, or correction of the underlying cause is most appropriate. Providers in the fertility and urology specialty can help distinguish between these forms through diagnostic testing.