Ordering Recommendation

When considering pyruvic acid testing, this is the preferred test.  This test reports concentrations for lactate, pyruvate, and the L:P ratio on the same specimen.

Mnemonic
LP RATIO
Methodology

Quantitative Enzymatic

Performed

Sun-Sat

Reported

1-2 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation

Patient should be fasting and at complete rest. Patient should 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.

Collect

Green (Sodium or Lithium Heparin).

Specimen Preparation

If whole blood is collected in a syringe, transfer immediately to green (sodium or lithium heparin) tube before preparing specimen.
1) 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 (ARUP supply #16567) available online through eSupply using ARUP Connect™ or contact Client Services at (800) 522-2787.
2) Mix well for 30 seconds then place in an ice bath for 10 minutes.
3) Centrifuge for 10 minutes at 1500 x g.
4) Decant 2 mL supernatant to an ARUP Standard Transport Tube and freeze. (Min: 1 mL)

Storage/Transport Temperature

Frozen.

Unacceptable Conditions
Remarks
Stability

Ambient: Unacceptable; Refrigerated: 2 days; Frozen: 4 weeks

Reference Interval
Available Separately Components Reference Interval
No Lactate 0.31-2.00 mmol/L
No Pyruvate 0.030-0.107 mmol/L
No L:P Ratio Not Applicable

Interpretive Data

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. An artificially high L:P ratio can be observed in acutely ill individuals. 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.

Compliance Category

Laboratory Developed Test (LDT)

Note

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 collection tube, pH of the supernatant will be too low for testing.

Hotline History
N/A
CPT Codes

84210; 83605

Components
Component Test Code* Component Chart Name LOINC
2007936 Lactic Acid 32693-4
2007937 Pyruvic Acid 14121-8
2007938 Lactate to Pyruvate Ratio 2550-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • Lactate Pyruvate Ratio
  • LP Ratio
  • Pyruvate (Pyruvic Acid)
Lactate to Pyruvate Ratio, Whole Blood