ABSTRACT
<p><b>AIM</b>To explore the causes of the difference in spermatogenic suppression between responders and non-responders in Chinese men treated with levonorgestrel (LNG) implants plus testosterone undecanoate (TU) injectable.</p><p><b>METHODS</b>The 16 Chinese volunteers treated were divided into two groups in regard to the sperm count during the treatment period, 7 men in the responder group (Group R), including 6 azoospermia and one severe oligozoospermia, and the remaining 9 in the non-responder group (Group N), including 4 oligozoospermia and 5 with sperm counts greater than 20 x 10(6)/mL. The differences in serum profiles of FSH, LH, T, LNG and T/LH ratio were compared between the two groups and the correlation between the seminal fluid parameters and serum reproductive hormones was analyzed.</p><p><b>RESULTS</b>The serum FSH level was lower in Group R than that in Group N (P<0.05), while the serum LH and LNG levels were higher in Group R than those in Group N (P<0.05). The sperm density (P<0.01, r=0.235), motility(P<0.01, r=0.326) and vitality (P<0.01, r=0.219) showed significantly positive correlation with the serum FSH level.</p><p><b>CONCLUSION</b>The blood LNG and T levels, the degree of FSH inhibition and/or the sensitivity of the pituitary-testis axis to exogenous steroids, as well as the individual spermatogenetic potential and the functional status of the Leydig cells may be factors bringing about individual differences in spermatogenic suppression in Chinese men treated with LNG and TU.</p>