Artifactually increased serum bicarbonate values in two horses and a calf with severe rhabdomyolysis.

This article discusses how severe muscle disease in two horses and a calf resulted in unusually high bicarbonate levels, likely due to an increased activity of the enzyme lactate dehydrogenase (LDH) and high levels of pyruvate.

Overview of Research Methodology

• The research started with the observation of unexpected high bicarbonate and anion gap values in the serum of two horses and a calf, all suffering from severe muscle disease, as confirmed by increased levels of aspartate aminotransferase and creatine kinase.
• An initial assumption was made that the anomaly could be attributed to a laboratory error, however, bicarbonate values produced from blood gas analysis were normal.
• The researchers postulated that increased LDH activity and higher concentrations of pyruvate may be causing the anomaly. They could potentially overwhelm the oxamate LDH inhibitor during the bicarbonate assay, leading to an increased consumption of NADH and a false high spectrophotometric reading.

Detailed Examination and Results

• LDH activity was found to be higher in all three subjects; hence, the researchers tried to mimic this scenario in a lab set-up by adding LDH and pyruvate to normal bovine serum.
• The concentration of bicarbonate was found to be artificially increased in relation to the level of LDH activity in the sample. Furthermore, the addition of pyruvate amplified this increase.

Conclusions and Implications from the Study

• The study concluded that the high serum LDH activity and elevated levels of pyruvate, as a result of severe muscle disease, could result in falsely elevated readings of bicarbonate values in serum when a routine enzymatic assay is used for testing.
• The findings have significant implications for clinical interpretations where high-bicarbonate values may be misleading in certain diseases associated with increased LDH activity and pyruvate concentrations.