Effects of normalization of plasma testosterone levels in hypogonadal men on plasma levels and urinary excretion of asymmetric dimethylarginine (ADMA)

This study analyzed the effects of normalization of plasma testosterone levels in ten hypogonadal men (aged from 35 to 69 ys) receiving testosterone (T) administration on plasma levels and urinary excretion of asymmetric dimethylarginine (ADMA), the most important endogenous inhibitor of nitric oxide (NO) synthase.

There was a small but significant decline in plasma ADMA values of approximately 10% (519±55 vs. 482±59 nmol/L, p=0.031) after 24 weeks of T administration of which 22 weeks had shown normalized plasma T levels >10 nmol/L (starting from mean T serum level of 4.0±2.72 nmol/L at baseline), with stable plasma T levels of app. 20 nmol/L over the last 16 weeks. Urinary excretion of ADMA (ADMA/Creatinine) did not change with testosterone treatment (p=0.43).

In view of the association of low T levels with a negative cardiovascular risk profile the outcome of this study impresses as a favorable effect of normalization of plasma testosterone on plasma ADMA, though most available studies on effects of T administration to hypogonadal men do not show beneficial effects on functions of the vascular wall.