Type B Lactic Acidosis: Diagnosis, Etiology and Treatment - An Educational Review.

Lactate elevation is commonly interpreted as a marker of tissue hypoxia; however, hyperlactatemia may occur despite adequate oxygen delivery and reflect diverse abnormalities in lactate production or clearance. Type B lactic acidosis is traditionally classified into three categories: underlying comorbid diseases, medication- and toxin-induced causes, and inborn errors of metabolism, making its recognition and management challenging. D-lactic acidosis represents a distinct disorder of lactate metabolism that may be overlooked by standard lactate assays. This educational review summarizes the pathophysiology and classification of type B lactic acidosis, reviews its major etiologies, and discusses D-lactic acidosis and hyperlactatemia during mechanical circulatory support. We propose a practical diagnostic algorithm for unexplained hyperlactatemia and review current therapeutic strategies, emphasizing treatment of the underlying cause. A structured approach may facilitate recognition of the mechanisms contributing to hyperlactatemia and guide targeted management, particularly in critically ill patients.