Pre-treatment estradiol does not predict testosterone response to clomiphene citrate

Clomiphene citrate (CC) is a selective estrogen receptor modulator (SERM) used to stimulate ovulation in women. CC is used off-label in men to increase levels of endogenous testosterone (T) while potentially improving semen parameters by downregulating the inhibitory feedback of estradiol (E) on the male hypothalamus. Our objective was to determine whether pre-treatment E level is associated with greater total testosterone (TT) response to treatment with CC in men with low T.

Following IRB approval (The University of Miami IRB No. 20170849), retrospective chart review was performed for all men prescribed CC (25 mg every other day) between January 1, 2015 and December 31, 2018. Age, body mass index (BMI), and prescription date were recorded for all patients. Pre- and post-treatment E, total T (TT), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels were recorded for all patients as well. Only men with pretreatment TT <300 ng/dL were included in the analysis in order to focus our study on men with low TT. Univariate linear regression analysis was performed to determinate the percent change in TT following CC treatment (dependent variable) and pre-treatment E and other variables including age, BMI, FSH, and LH (independent variables).

A total of 69 men with TT <300 ng/dL received CC 25 mg every other day. Mean age and BMI were 33.3±7.31 years and 35.4±5 kg/m² respectively. Median pre-treatment E, TT, FSH, and LH were 18 [11.35-24.6] pg/mL, 226 [156-262] ng/dL, 5.1 [2.98-8.05] mIU/mL, and 4.5 [2.6-6.8] mIU/mL respectively. Post-treatment TT was 389 [263-592] ng/dL and TT% change was 102 [45.51-176.75]. Univariate linear regression showed that pre-treatment E (B=-0.595; R²=0.001; P=0.757) did not significantly predict TT% change. TT% change could be significantly predicted by age in years (B=-7.428; R²=0.057; P=0.048), pre-treatment FSH (B=-8.362; R²=0.068; P=0.041), and pre-treatment LH (B=-20.67; R²=0.096; P=0.027).

Pre-treatment E level does not appear to predict treatment response with CC in men with low T.