The interpretation of blood lactate results, especially with respect to elevated values, is often based on inaccurate assumptions. We decided upon this topic for the Clinical Focus Review1  based on our observations of clinicians from all disciplines who routinely gave fluid boluses to normalize the lactate of patients with hemodynamic stability, euvolemia, and normal acid base balances without ruling out the reason for the hyperlactatemia.

We are in agreement with Woehlck et al.2  that lactate can be elevated from stored red blood cells as well as the inability to clear during massive transfusions. The studies of lactate metabolism in adipocytes were biochemically complex, extensive, and data-rich. However, we feel that the applicability of in vitro rat cell results and studies of Drosophila to humans is too premature.3 

The comments of Bahlmann and Werner-Moller4  from Sweden about our Clinical Focus Review, which was written in Boston, are reminiscent of “The Great Trans-Atlantic Acid-Base Debate” published in 1965.5  Their opinions are rooted on the role of lactate in the strong ion difference, based on the calculations of Stewart6  for the determination of acidosis. In vivo, the interactions of plasma, erythrocytes, and the interstitium are complex, and the Stewart approach is complementary to other alternatives for acid–base assessments but is not definitive.7  It is not uncommon to have a metabolic acidosis ruled out with an increased lactate that is inadequate to explain the severity of the acidosis or the elevation in the anionic gap.8  Critically ill patients may present severe hyperlactatemia with normal values of pH, bicarbonate, and base excess as a result associated with hypochloremic alkalosis.9 

The key to lactate-associated metabolic acidosis is not necessarily the stoichiometry of acid–base balance but the reason for its elevation.

Dr. Pino reports financial relationships with Morrison Mahoney (Boston, Massachusetts) and Ratcliff Harten Galamaga LLP (Providence, Rhode Island) for expert legal testimony. Dr. Singh declares no competing interests.

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