Hyponatremia, hypernatremia and impairment of functional, psychological and sexual domains

To determine the influence of serum sodium on physical, psychologic and sexual function.

This is a cross-sectional survey on 3340 community-dwelling men aged 40-79 years from a prospective cohort study in eight European countries, the European Male Ageing Study (EMAS). Participants filled-out the Short Form-36 (SF-36), the Physical Activity Scale for the Elderly (PASE), and the EMAS sexual function questionnaire. For all the analyses, serum sodium corrected for glycaemia ([Na⁺]_G) was used.

The relationship between [Na⁺]_G and SF-36 physical function score (F = 3.99; p = 0.01), SF-36 mental health score (F = 7.69; p < 0.001), and PASE score (F = 14.95; p < 0.001) were best described by a quadratic equation, with worse scores for [Na⁺]_G in either the lowest or the highest ends of the range. After dividing the sample into [Na⁺]_G < 136 mmol/L (n = 81), 136-147 mmol/L (n = 3223) and > 147 mmol/L (n = 36), linear regression analyses with linear spline functions adjusted for confounders did not confirm these relationships. Similarly, erectile dysfunction and [Na⁺]_G, were in a quadratic relationship (F = 9.00; p < 0.001). After adjusting for confounders, the linear regression with spline functions denoted a significantly worsened erectile function for increases in serum [Na⁺]_G > 147 mmol/L (B = 0.15 [0.04;0.26], p < 0.01) but no relationship with [Na⁺]_G < 136 mmol/L. Likewise, the relationship of [Na⁺]_G with concerns about sexual dysfunction was confirmed only for men with serum [Na⁺]_G > 147 mmol/L.

This is the first study supporting an association between [Na⁺]_G and sexual function. A worsening of erection and concerns about sexual function were observed for the highest values of [Na⁺]_G, independently of other relevant factors.