Figure 4.

GnRH pulse frequency and LH pulse amplitude in healthy male volunteers (A and C) and IHH men on GnRH therapy maintained at a constant 2 h frequency (B and D) during medical castration for 7 d with either no sex steroid add-back or replacement with T or E₂ from d 4–7. a, Significant difference from BL, P < 0.005; b, significant difference from BL, P < 0.05; c, significant difference between d 3–4 and d 6–7, P < 0.05; d, significant difference between d 3–4 and d 6–7, P < 0.005.