AUA 2017: Calculated Free T and T:E Ratio but not Total Testosterone and Estradiol Predict Low Libido

Boston, MA ( Libido is thought to be influenced by hormonal milieu, particularly testosterone. The knowledge about the role of estradiol in male sexual function has been found to be more important than originally thought. The estradiol cut-off point of 5 ng/dL in hypogonadal men is thought to directly affect libido. Dr. Gupta presented a study assessing the impact of sex hormones on libido specifically in a cardiac patient population.

The study focused on 200 men in a cardiology practice who completed the IIEF-15, ADAM, and previous ED treatment questionnaires. Additionally all patients had serum total testosterone (T), estradiol (E), and sex hormone binding globulin (SHBG) levels measured via morning lab draws. Their free testosterone (CFT) was calculated using an online ISSM calculator. Patients that were diagnosed for hypogonadism in the past or who were currently on medications possibly affecting T levels were excluded. Hormonal levels were correlated to responses to the IIEF questions 11 and 12 (IIEF11, IIEF12), focusing on libido.

Results demonstrated the mean total T level to be 310 ng/dL with CFT of 5.4 ng/dL. Mean E levels were 4.4 ng/dL and mean T:E ratio was 8.2. Importantly, 55% of patients had T levels less than 300 ng/dL and 74% of patients had a CFT < 6.5 ng/dL. Negative correlation was found between estradiol and IIEF11 and IIEF12, but was not statistically significant. However, a positive correlation was found between IIEF11 and IIEF12 and CFT and T:E ratio (p=0.007, p=0.009, respectively). At a cutoff of E=5ng/dL, no difference was found for either hypogonadal or eugonadal men on the IIEF11 or IIEF12.

In summary, CFT and T:E ratio were predictive of positive libido response on IIEF11 & 12 questions in the IIEF questionnaire. Estradiol, even at a cutoff of 5 ng/dL, was not independently associated with improved libido. Surprisingly, no correlation was found between total testosterone and IIEF11 (desire frequency). The effect of testosterone and estradiol on libido requires further research with prospective studies.

Presented By: Nikhil Gupta, Springfield, IL

Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre

at the 2017 AUA Annual Meeting - May 12 - 16, 2017 – Boston, Massachusetts, USA