Interference and blood sample preparation for a pyruvate enzymatic assay

Area of Science:

• Clinical Chemistry
• Biochemical Assays
• Circulatory Failure Diagnostics

Background:

• Pyruvate enzymatic assays are crucial for assessing circulatory failure severity.
• Lactate dehydrogenase catalyzes pyruvate to lactate conversion in whole blood.
• Investigated sample collection and preparation factors influencing pyruvate assay results.

Purpose of the Study:

• Evaluate the impact of deproteinization timing on pyruvate levels.
• Determine optimal sample storage temperatures (room temperature vs. 4°C) before deproteinization.
• Assess the effect of hemolysis on blood pyruvate assay accuracy.

Main Methods:

• Analyzed 25 whole blood specimens, dividing samples for different storage and deproteinization conditions.
• Used 8% perchloric acid (PCA) for deproteinization at hourly intervals up to 6 hours, plus overnight storage.
• Assayed pyruvate levels using a COBAS Centrifugal Analyzer after deproteinization and supernatant storage at room temperature or 4°C.

Main Results:

• Storing whole blood at room temperature showed minimal pyruvate increase (<13.3%) if deproteinized promptly.
• Storing whole blood at 4°C significantly reduced pyruvate levels (37.8%–62.2%).
• Hemolysis artifactually increased pyruvate concentration by 33.7%.

Conclusions:

• Immediate deproteinization of whole blood at room temperature is acceptable for pyruvate assays.
• Avoid storing whole blood samples in ice baths for transport due to significant pyruvate degradation.
• Hemolyzed samples are unsuitable for accurate blood pyruvate enzymatic assays.