When healthy men take a high dose of testosterone for 10 weeks, their body shuts down some of its own hormone production—like turning off a faucet—because it thinks it already has enough.

A double-blind, placebo-controlled RCT in healthy adult men (n=30–50) receiving either 600 mg/week of exogenous testosterone (e.g., testosterone enanthate) or a placebo injection for 10 weeks, with serum LH and FSH measured at baseline, week 5, and week 10; primary outcome is percentage reduction in LH and FSH from baseline.

A prospective cohort study in healthy men (n=50–100) self-administering 600 mg/week of testosterone for 10 weeks under medical supervision, with serial measurements of LH and FSH at baseline, week 4, week 8, and week 10; analysis focuses on within-subject percentage change and proportion achieving >50% suppression.

A single-arm study in healthy men (n=20–30) receiving 600 mg/week testosterone for 10 weeks, with LH and FSH measured before and after intervention; statistical comparison of pre- vs. post-treatment levels to determine if suppression exceeds 50%.

A case series reporting LH and FSH levels in 10–15 healthy men who received 600 mg/week testosterone for 10 weeks as part of clinical care or research, with documented pre- and post-treatment hormone levels.

An animal study (e.g., in male rats or non-human primates) administering supraphysiologic testosterone (dose-equivalent to 600 mg/week human) for 10 weeks and measuring pituitary LH/FSH secretion or hypothalamic GnRH suppression.