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Test ID LAPYP Lactate Pyruvate Panel, Plasma


Ordering Guidance


This test does not measure D-lactate, an uncommon, often undiagnosed cause of lactic acidosis. If D-lactate testing is needed, order DLAU / D-Lactate, Urine (preferred) or DLAC / D-Lactate, Plasma.

 

Analytes from this test are included in test MMPP / Mitochondrial Metabolites, Plasma. If ordered together, this test may be canceled.



Specimen Required


Collection Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: Green top (lithium heparin)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot plasma into plastic vial.


Useful For

Diagnosing and monitoring patients with lactic acidosis

 

Monitoring lactate-to-pyruvate ratios

Method Name

Gas Chromatography-Mass Spectrometry (GC-MS)

Reporting Name

Lactate Pyruvate Panel, P

Specimen Type

Plasma

Specimen Minimum Volume

0.1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Frozen (preferred) 90 days
  Ambient  7 days
  Refrigerated  7 days

Clinical Information

Lactic acid (lactate) is primarily produced from glucose metabolism via the glycolytic pathway. Although primarily metabolized by the liver, other tissues also use small amounts of lactate. Typically, the amount of lactate produced parallels the amount utilized. Both the rates of lactate production and liver clearance impact the lactate concentration in blood. Lactic acidosis, or the accumulation of excess lactate, results from a combination of increased lactate production with decreased utilization.

 

Patients experiencing lactic acidosis present with tachypnea, weakness, and fatigue. Untreated, patients may develop confusion and progress to coma. Lactic acidosis may be associated with hypoxic conditions (eg, shock, hypovolemia, heart failure, pulmonary insufficiency), metabolic disorders (eg, diabetic ketoacidosis, malignancies, inborn errors of metabolism), and toxin exposures (eg, ethanol, methanol, salicylates).

 

Pyruvic acid, an intermediate metabolite, plays an important role in linking carbohydrate and amino acid metabolism to the tricarboxylic acid cycle, the fatty acid beta-oxidation pathway, and the mitochondrial respiratory chain complex. However, pyruvic acid levels alone have little clinical utility.

 

Combined analysis of lactate and pyruvate may suggest an inborn error of metabolism when elevations of both analytes are observed or when there is an abnormal lactate-to-pyruvate (L:P) ratio. For example, several mitochondrial respiratory chain disorders exhibit elevated L:P ratios. Mitochondrial disorders vary widely in both clinical presentation and age of onset. Patients commonly present with neurologic and myopathic features. In addition, patients may experience involvement of multiple organ systems with features such as myopathy, ophthalmoplegia, ptosis, cardiomyopathy, sensorineural hearing loss, optic atrophy, pigmentary retinopathy, diabetes mellitus, encephalomyopathy, seizures, and stroke-like episodes.

 

A low L:P ratio is observed in inherited disorders of pyruvate metabolism including pyruvate dehydrogenase complex (PDHC) deficiency. Clinical presentation of PDHC deficiency can range from fatal congenital lactic acidosis to relatively mild ataxia or neuropathy. The most common features observed in infants and children with PDHC deficiency are developmental delay, hypotonia, seizures, and ataxia. Other manifestations may include congenital brain malformations, degenerative changes including Leigh disease and facial dysmorphism.

Reference Values

LACTIC ACID

≤ 4000.0 nmol/mL

 

PYRUVIC ACID

≤ 350.0 nmol/mL

Interpretation

An elevated lactate-to-pyruvate (L:P) ratio may indicate inherited disorders of the respiratory chain complex, tricarboxylic acid cycle disorders, and pyruvate carboxylase deficiency. Respiratory chain defects usually result in L:P ratios above 20.

 

A low L:P ratio (disproportionately elevated pyruvic acid) may indicate an inherited disorder of pyruvate metabolism. Defects of the pyruvate dehydrogenase complex result in L:P ratios below 10.

 

The L:P ratio is characteristically normal in other patients. An artifactually high ratio can be found if the patient is acutely ill.

 

Cerebrospinal fluid (CSF) L:P ratio may assist in evaluation of patients with neurologic dysfunction and normal blood L:P ratios. Blood and CSF specimens should be collected at the same time.

Clinical Reference

1. Munnich A, Rotig A, Cormier-Daire V, Rustin P: Clinical presentation of respiratory chain deficiency. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed February 17, 2022. Available at http://ommbid.mhmedical.com/content.aspx?bookid=2709&sectionid=225086827

2. Robinson BH: Lactic acidemia: Disorders of pyruvate carboxylase and pyruvate dehydrogenase. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed February 17, 2022. Available at http://ommbid.mhmedical.com/content.aspx?bookid=2709&sectionid=225087140

3. Shoffner JM: Oxidative phosphorylation diseases. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019 Accessed February 17, 2022. Available at http://ommbid.mhmedical.com/content.aspx?bookid=2709&sectionid=225088339

Day(s) Performed

Tuesday

Report Available

3 to 9 days

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

83605

84210

LOINC Code Information

Test ID Test Order Name Order LOINC Value
LAPYP Lactate Pyruvate Panel, P In Process

 

Result ID Test Result Name Result LOINC Value
616797 Interpretation 59462-2
616794 Lactic acid 2524-7
616795 Pyruvic acid 32338-6
616796 Reviewed by 18771-6