The aim of this study was to evaluate the effect of vitamin D replacement in patients with lower urinary tract symptoms (LUTS)/erectile dysfunction (ED) who did not respond to tadalafil 5 mg treatment.

Patients who applied to the Andrology Clinic with LUTS/ED between September 2017 and August 2020 and used 5 mg Tadalafil daily for treatment and did not benefit from treatment for one month were included in the study. Vitamin D levels of the patients were analyzed and Vitamin D3 100,000 IU/week oral  therapy was administered for a month to the patients with low levels of Vitamin D(<20ng/ml).The values of the patients before and after Vitamin D replacement were compared.

A total of 84 patients were included in the study.The mean age was 49.175±11.63(28-70) years and the mean BMI was 25.93±6.82(18.26-37.87). Testosterone levels of the examined patients were 3.45±0.99 ng/ml. After one month of Vitamin D replacement + Tadalafil 5 mg/d treatment, the IIEF-EF (pre-treatment: 10.73±6.12, post-treatment: 24.18±4.87; p=0.001) and IPSS (pre-treatment: 9.12±7.16, post-treatment: 3.11±1.08; p=0.003) scores of the patients improved significantly. Testosterone levels of the patients increased to 3.77±1.23 ng/ml (p<0.001) and 25(OH)D levels increased to 30.50±7.56 ng/ml (p<0.001).
There was a moderately significant linear correlation between IIEF-EF scores and Vitamin D levels after the treatment (p<0.001; r=0.661) There was a moderate linear correlation between IIEF-EF scores and testosterone levels (p<0.001; r=0.674). There was a moderately significant negative correlation between IIEF-EF scores and IPSS scores after the treatment (p=0.003, r=0.458). A weak positive correlation was found between testosterone levels and Vitamin D levels (p=0.013; r=0.321). There was no significant correlation between IPSS scores and testosterone levels (p=0.356; r=0.221)

The study results showed that Tadalafil 5 mg treatment together with Vitamin D replacement had improvement on erectile functions and LUTS in patients with Vitamin D deficiency who took Tadalafil for ED and did not respond. Moreover, it was shown that the improvement in Vitamin D levels was moderately correlated with erectile functions. The results of the present study suggest that the efficacy of Tadalafil increases with Vitamin D replacement administered by examining 25(OH) Vitamin D level in patients who do not respond to Tadalafil 5mg treatment and do no have sufficient improvement in their IIEF-EF scores. It is considered that this is caused by both the efficacy of Vitamin D replacement in the endothelial system and in increasing testosterone levels. There are similar studies in the literature; however, this is the first study, to the best of our knowledge, to evaluate the efficacy of the combined treatment after treatment ineffectiveness.

Low levels of Vitamin D in LUTS/ED patients have an effect on tadalafil non unresponsiveness. With vitamin D supplementation, patients' LUTS and ED symptoms improved. Evaluation of Vitamin D levels is important to improve treatment response, especially in patients who do not respond to PDE-5 inhibitors. Further studies are needed the role of Vitamin D in the pathophysiology of ED.

Continence 2S2 (2022) 100392
DOI: 10.1016/j.cont.2022.100392