Lactate to Pyruvate Ratio, Whole Blood

Also known as: LP RATIO

Clinical Use

Use

The blood lactate to pyruvate (L:P) ratio is used to distinguish between pyruvate dehydrogenase deficiency and other causes of congenital lactic acidosis. In conjunction with an elevated lactate, an L:P ratio greater than 30 suggests inherited disorders of the respiratory chain complex or tricarboxylic acid cycle disorders. In conjunction with an elevated lactate, an L:P ratio less than 25 suggests a defect in pyruvate metabolism. Abnormal concentrations of lactate, pyruvate, and the L:P ratio are not diagnostic for any single disorder and must be interpreted in the context of the individual's clinical presentation and other laboratory studies.

Special Instructions

Not provided.

Limitations

An artificially high L:P ratio can be observed in acutely ill individuals. If addition to perchloric acid is delayed, lactate concentration of whole blood increases by approximately 30 percent after 30 minutes, 50 percent after 1 hour, and 75 percent after 2 hours at room temperature. If less than 1 mL of blood is added to the collection tube, the pH of the supernatant will be too low for testing.

Test Details

New York Approved

Methodology

Automated Analyzer (Clinical Chemistry)

Biomarkers

3 components

Lactate Measurement • Clinical ChemistryPyruvate Measurement • Clinical ChemistryLactate to Pyruvate Ratio Measurement • Clinical Chemistry

LOINC Codes

Order Codes

14121-8 - Pyruvate Bld-sCnc
2550-2 - Lactate/Pyruvate Bld-sRto
32693-4 - Lactate Bld-sCnc

Result Turnaround Time

1-2 days

Specimen

Whole Blood

Volume

1 mL

Minimum Volume

1 mL

Container

Green (Sodium or Lithium Heparin) tube

Collection Instructions

Immediately after blood is drawn, add exactly 1 mL whole blood to a chilled pyruvate collection tube containing 2 mL 8 percent (w/v) perchloric acid. Mix well for 30 seconds then place in an ice bath for 10 minutes. Centrifuge for 10 minutes at 1500 x g. Decant 2 mL supernatant to an ARUP Standard Transport Tube and freeze.

Patient Preparation

Patient should be fasting and at complete rest. Avoid any exercise of the arm or hand before or during collection. Draw the specimen without the use of a tourniquet or within three minutes of applying the tourniquet, but before releasing the tourniquet.