[Lactic Acidosis and Other Misunderstandings].

Area of Science:

• Biochemistry
• Intensive Care Medicine
• Metabolic Disorders

Background:

• Lactic acidosis is a common clinical issue in intensive care settings.
• Current understanding of lactic acidosis involves several misconceptions regarding its biochemical basis.
• Physiological roles of lactate are often overlooked, leading to its misclassification as a metabolic waste product.

Purpose of the Study:

• To clarify the biochemical processes underlying lactic acidosis.
• To address and correct common misconceptions about lactate metabolism and its role in acidosis.
• To re-evaluate the utility of lactate levels as indicators of tissue oxygenation.

Main Methods:

• Biochemical pathway analysis of lactate production from pyruvate.
• Review of physiological functions of lactate in energy metabolism.
• Critical evaluation of clinical data associating lactate levels with acidosis and tissue oxygenation.

Main Results:

• Lactate is a crucial energy carrier produced from pyruvate, consuming hydrogen ions (H+).
• Lactate production itself does not directly cause acidosis; H+ consumption indicates otherwise.
• Elevated lactate levels are not reliable indicators of underlying pathophysiological processes or tissue hypoperfusion.

Conclusions:

• Lactate is a physiological intermediate essential for energy transport, not a metabolic byproduct.
• The direct causation of acidosis by lactate production is biochemically inaccurate.
• Clinical interpretation of elevated lactate levels requires re-evaluation, as it is not a definitive marker for tissue oxygenation status.