To the Editor:
Risk factors and comorbidities associated with erectile dysfunction (ED) in patients with gout include diabetes mellitus, hypertension, advanced age, obesity, hyperlipidemia, metabolic syndrome, certain medications, and tobacco abuse. We suggested1 that hyperuricemia and inflammation may be independent risk factors for ED in addition to the conventional ones. Lv and Chen2 suggest another possible independent risk factor for ED in patients with gout: low levels of Vitamin D, and they question the need to give Vitamin D supplementation to these patients.
Vitamin D might have both positive and negative effects on the cardiovascular system and thus on ED, depending on the doses used. In 2007, Zittermann, et al3 suggested a “U” curve to explain the potential dual effect of Vitamin D on the cardiovascular system — an increased cardiovascular risk at both the low (mainly secondary to the reduced antiinflammatory and endothelial-protective effects) and high (secondary to the increased calcemic and phosphatemic effects and stimulation of FGF23) Vitamin D levels. For the dual effect to be studied, the study duration should be sufficiently long; although the antiinflammatory effect might be evident in a short time, to see the effects related to calcium and phosphorus metabolism might require a longer observation time.
The evidence base for effects of Vitamin D on bone health is strong and supported by randomized clinical trials. However, the evidence base for the effects of Vitamin D on nonskeletal disease such as cardiovascular disease and ED is inconclusive, inconsistent, and unable to support such conclusions4. Thus, the question of the effect of Vitamin D levels as well as Vitamin D supplementation on serum urate and ED in patients with gout is interesting and may warrant further study.