Erroneously low serum CO2 level (sCO2) determination or pseudohypobicarbonatemia (PHB) has been reported in severe hypertriglyceridemia.1–4 Artifactual sCO2 values may occur due to lipid interference in some analyzers (primarily Abbott Architect).4 Analyzers measure sCO2 through a phosphoenolpyruvate (PEP) carboxylase reaction. CO2 and PEP are converted to phosphate and oxaloacetate, which is reduced to malate, resulting in the oxidation of nicotinamide adenine dinucleotide. The decrease in absorbance is proportional to the sample’s CO2 content,5 and triglycerides (TG) can disrupt spectrophotometry by absorbing light.