Introduction

Erectile dysfunction (ED) has been associated to lower serum total testosterone (TT) levels. The utility of free T over TT is debatable. Calculated empirical estimates of free testosterone (cFT) also are commonly used and accepted. We aimed to assess the relative impact of low TT and low cFT on androgen-related sexual symptoms in men with ED as a primary compliant.

Methods

Data from 485 consecutive men were analysed. Comorbidities were scored with the Charlson Comorbidity Index (CCI). Patients completed the International Index of Erectile Function (IIEF) and the Beck's inventory for Depression (BDI). Descriptive statistics tested the differences between the referent group of patients with normal TT (defined as TT>3ng/ml according to the Endocrine Society) and normal cFT (>0.065 ng/ml) (Group 1) with those who had normal TT/low cFT (Group 2); low TT/normal cFT (Group 3); and, low TT/low cFT (Group 4). Logistic regression models tested the association between clinical predictors and pathologic psychometric scores.

Results

Overall, 338 (69.6%), 44 (9.1%), 34 (7.0%) and 69 (14.3%) patients were in Group 1, 2, 3 and 4, respectively. Compared to Group 1, Group 2 patients were older (p<0.001), had higher BMI (p<0.01) and a greater proportion of CCI>=1 (p=0.006). Likewise, Group 2 presented lower IIEF-EF (p=0.07), IIEF-SD (p=0.04), IIEF-OF (p=0.007) and lower BDI scores (p=0.02) than Group 1. Similar findings were found for Group 4 vs. Group 1. Conversely, Group 3 patients were older (p<0.001) than in Group 1, but had similar psychometric scores. At multivariable analysis, low cFT, either with normal or low TT, achieved independent predictor status for pathologic IIEF domains and BDI scores, after accounting for age, CCI, and BMI. Conversely, low TT/normal cFT was not associated with pathological psychometric scores.

Conclusions

Low cFT, even with normal TT, was associated with a worse clinical profile and impaired sexual and depressive parameters compared to normal TT/normal cFT in a cohort of ED patients. Of clinical relevance, normal cFT, irrespective of low TT, was not associated with signs and symptoms suggestive for testosterone deficiency.

Funding

none