Introduction: Klinefelter(KF) men commonly exhibit non obstructive azoospermia and hypogonadism. This study aims to evaluate if sperm retrieval rate(SSR) could be improved by implementing a new protocol of HCG treatment prior to mTESE. Methods: KF men prospectively added to our database were compared to a previous retrospective group who had not undergone hormonal stimulation. Demographic data, previous testosterone therapy, duration of endocrine stimulation, pre-/ post-stimulation levels (T, FSH, LH), successful SSR, Johnsen score and total number of vials of sperm retrieved. Men started on 2000units of HCG twice/week and the dosage altered depending on response. Stimulation continued for a minimum of 6 months. Success criteria for mTESE was defined as at least 1 vial of viable sperm retrieved. Results: Sixty-four KF men underwent mTESE, out of which 39 men received stimulation therapy for a mean duration of 11.8 ± 8.5 month. No significant differences regarding mean age, Johnsen score and successful sperm retrieval(SSR) rate were detected between the 2 groups. The mean pre-stimulation serum testosterone level was 6.1±3.7nm/L and it increased to 9.4±6.9nm/L post stimulation. We demonstrated that serum testosterone levels significantly increased after endocrine stimulation (6.1 ± 3.7 nm/L vs 9.8 ± 6.9 nm/L, p<0.001) with a mean change in serum testosterone (?T) of 4.9 nm/L. Baseline serum T level in the unstimulated group(10.5±4.9 nm/L) was significantly different to the baseline T of the stimulated group (P=0.001). The endocrine stimulation removed the significant difference between baseline serum T level in the stimulated group(9.8 versus 10.5nmol/l). This may explain why SSR rates were ultimately the same. The SSR was 28% (17/39 in the stimulated group and 7/25(28%) in the unstimulated group. Comparing both sets of men who had successful vs unsuccessful mTESE – a higher level of serum T correlated with a successful sperm retrieval(p=0.036). Conclusions: Our study shows that there is a significant improvement of serum T concentration following endocrine stimulation therapy in KF men and that a higher level of serum T correlates with successful SSR. We did not demonstrate that stimulation increases the chance of success when compared to non-stimulated men but this is likely to be due to a significant difference in baseline serum T between the 2 groups. The induction protocol of twice weekly HCG injections for 6 months was acceptable to patients and no major side effects experienced. SOURCE OF Funding: None
