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Test ID: PYR Pyruvic Acid, Blood

Reporting Name

Pyruvic Acid, B

Useful For

Screening for possible disorders of mitochondrial metabolism, when used in conjunction with blood lactate collected at the same time, to determine the lactate-to-pyruvate ratio

Clinical Information

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. Though isolated elevated pyruvate is not diagnostic of any inborn error of metabolism, analysis with lactate may suggest an inborn error of metabolism as some present with lactic acidosis or a high lactate-to-pyruvate (L:P) ratio.

 

The L:P ratio is elevated in several, but not all, mitochondrial respiratory chain disorders. Mitochondrial disorders vary widely in presentation and age of onset. Many mitochondrial disorders have neurologic and myopathic features and may involve multiple organ systems. Determination of lactate, pyruvate, and L:P ratio in cerebrospinal fluid is helpful in directing attention toward a possible mitochondrial disorder in cases with predominantly neurologic dysfunction and normal blood lactate levels, though further confirmatory testing will be required to establish a diagnosis.

 

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 in infants and children with PDHC deficiency are delayed development and hypotonia. Seizures and ataxia are also frequent features. Other manifestations can include congenital brain malformations, degenerative changes including Leigh disease, and facial dysmorphism.

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.

Testing Algorithm

See Epilepsy: Unexplained Refractory and/or Familial Testing Algorithm in Special Instruction.

Analytic Time

6 days

Day(s) and Time(s) Performed

Monday, Thursday; Varies

Clinical Reference

1. Munnich A, Rotig A, Cormier-Daire V, Rustin P: Clinical Presentation of Respiratory Chain Deficiency. In The Online Metabolic and Molecular Bases of Inherited Disease. Edited by D Valle, S Antonarakis, A Ballabio, et al.  McGraw-Hill. Accessed 1/13/2020. 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 The Online Metabolic and Molecular Bases of Inherited Disease. Edited by D Valle, S Antonarakis, A Beaudet, et al. McGraw-Hill. Accessed 1/13/2020. Available at http://ommbid.mhmedical.com/content.aspx?bookid=2709&sectionid=225087140

3. Shoffner JM: Oxidative Phosphorylation Diseases. In The Online Metabolic and Molecular Bases of Inherited Disease. Edited by D Valle, S Antonarakis, A Ballabio, et al. McGraw-Hill. Accessed 1/13/2020. Available at http://ommbid.mhmedical.com/content.aspx?bookid=2709&sectionid=225088339

Method Name

Spectrophotometry (SP)

Specimen Type

Whole blood


Additional Testing Requirements


This test does not calculate the lactate:pyruvate ratio. To obtain this information, both this test and LAA / Lactate, Plasma must be ordered. The ratio can be calculated from the results obtained from these tests.



Specimen Required


Call 800-533-1710 or 507-266-5700 to order special collection tube.

 

Patient Preparation: Fasting (at least 4 hours)

Supplies: Perchloric Acid–Pyruvate Tube (T012)

Container/Tube: Special collection tube containing 2.5 mL of 6% perchloric acid

Specimen Volume: Exactly 1 mL

Collection Instructions:

1. Special collection tube must be prechilled prior to collection.

2. Draw enough blood directly into syringe to add exactly 1 mL of blood to the prechilled special collection tube.

3. Once drawn, immediately transfer blood to the prechilled, special collection tube and shake vigorously to mix.

Additional Information:

1. Check expiration date before using. Supplied collection tube expires 12 months after preparation.

2. If perchloric acid spills, obtain new, prechilled tube.


Specimen Minimum Volume

See Specimen Required

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole blood Refrigerated 15 days PYRUVATE

Reference Values

0.08-0.16 mmol/L

 

NIH Unit

0.7-1.4 mg/dL

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 U.S. Food and Drug Administration.

CPT Code Information

84210

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PYR Pyruvic Acid, B 14121-8

 

Result ID Test Result Name Result LOINC Value
8657 Pyruvic Acid, B 14121-8
7729 Pyruvic Acid, B 2905-8

Forms

1. Biochemical Genetics Patient Information (T602) in Special Instructions.

2. If not ordering electronically, complete, print, and send an Inborn Errors of Metabolism Test Request (T798) with the specimen.

Mayo Clinic Laboratories | Neurology Catalog Additional Information:

mml-Behavioral, mml-Cerebrovascular, mml-Epilepsy, mml-Headache, mml-Movement-Disorders, mml-Demyelinating-Diseases, mml-Neuromuscular, mml-Pediatric, mml-Neurometabolic