Asymmetric and symmetric dimethylarginines: metabolism and role in severe sepsis.

Asymmetric dimethylarginines (ADMA) and symmetric dimethylarginines (SDMA) are markers of protein breakdown; both compete with arginine for cellular transport and are excreted in urine. In addition, ADMA is a nonselective inhibitor of NO synthase, and is also metabolized by dimethylarginine-dimethylaminohydrolase (DDAH), a specific hydrolase whose activity in stress is controversial [1]. While the ADMA increase is associated with adverse events in many critical conditions, little attention has been focused on the role of SDMA [2].