SAT-152 Clomiphene for the Treatment of Testosterone Deficiency: Effects on Pituitary Axis Function

Abstract Disclosure: A.K. Clift: I am an employee of Manual (Menwell Ltd), a healthcare provider that provides testosterone replacement therapy. J. Foster: I am an employee of Manual (Menwell Ltd), a healthcare provider that provides testosterone replacement therapy. D.R. Huang: I am an employee of Manual (Menwell Ltd), a healthcare provider that provides testosterone replacement therapy. Clomiphene is a selective estrogen receptor modulator that can be used for the treatment of testosterone deficiency (TD) in men. Use of this agent seeks to stimulate endogenous testosterone (T) production and may at least partially preserve spermatogenesis. Therefore, it could be especially useful in hypogonadic men seeking to preserve fertility. We sought to explore the trends in pituitary function (circulating LH, FSH), total T levels, and haematocrit (a safety marker) associated with the use of clomiphene in the context of TRT over a 6 month period. We undertook a retrospective cohort study of men prescribed clomiphene for TD at a UK healthcare provider. All men had total T <12.2nmol/L or free T <0.226nmol/L at baseline. Baseline and follow-up blood results for LH, FSH, total T and haematocrit (Hct) were extracted. Mixed models with repeated measures were used to model trends in these parameters in the cohort. Marginal (average) values of these markers were calculated at two-monthly intervals with 95% confidence intervals, adjusting for baseline age. Kaplan-Meier methods estimated the incidence rates of Hct>0.54. 279 men were included in the cohort; mean total T at baseline was 9.98nmol/L (SD 2.66), mean free T at baseline was 0.212nmol/L (SD: 0.55). The mean age at initiation of clomiphene was 42 years (SD 10.53, range 22 to 75). There was a significant increase in total T at 6 months (22.61, 95% CI: 21.09 to 24.13], p<0.01). Between baseline and 6 months, there were no significant changes in LH (4.59 [95% CI: 4.13 to 5.07] vs. 4.32 [95% CI: 1.66 to 6.97]) or FSH (4.20 [95% CI: 3.78] vs. 3.81 [95% CI: 1.65 to 5.98]). In total, 7 men (2.50%) had a recorded Hct>0.54 during follow-up, with a Kaplan-Meier estimated incidence of 12.36% at 6 months, with no significant difference in marginal Hct values between baseline and end of follow-up (0.47 [95% CI: 0.46 to 0.47] vs. 0.47 [95% CI: 0.45 to 0.50], respectively). Treatment with clomiphene within TRT strategies was associated with preservation of pituitary axis function over 6 months, with stable LH and FSH observed during this period. This suggests a clinical utility for clomiphene in men who would benefit from preserving their pituitary axis and endogenous testosterone production, or wish to maintain fertility. Further study such as prospective analysis of sperm parameters and their correlations with biochemical markers of pituitary hormone function are warranted, as are studies exploring the role of clomiphene monotherapy. Presentation: Saturday, July 12, 2025