[The role of lactate besides the lactic acidosis]

Lactic acidosis (LA) is the most common form of metabolic acidosis defined by values of lactate greater than 5 mmol / l and by a pH <7.34. The pathogenesis of LA involves hypoxic (type A) and non hypoxic (type B) causes which are often coexisting. Lactic acidosis is usual in hospitalized population especially in subjects in intensive care units, in which lactate levels on admission could be predictors of mortality even in the absence of organ dysfunction or shock. The outcome is mainly dependent on the cardiovascular effects of acidosis. In subjects with cardiogenic shock, the increased lactate/pyruvate ratio, detectable at onset, is correladed with mortality. An early assessment of blood and tissue lactate levels could play a role in the therapeutic management as well as in outcome. LA could be a unfavorable prognostic factor in cancer. The lactate would act also as "signal molecule" and as a promoting factor in angiogenesis and tumor progression. In the presence of risk factors for LA the role of metformin may be overrated. Despite the doctrinal progress to understand the pathogenesis and pathophysiology, there is not univocal consensus on the therapeutic treatment of LA. The identification and the attempt to remove the cause of acidosis are main aims; treatment with sodium bicarbonate is a matter of debate as the data on the cardiovascular effects and mortality are unclear. The therapy with carbicarb, dichloroacetate or THAM has shown no specific advantages in terms of mortality. In experimental models of LA and shock the use of sodium-hydrogen exchanger-1 (NHE1) selective inhibitors reduces cell damage and inflammatory cytokines synthesis; it also improves cardiac performance and decreases mortality.