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HelpTest Code PYR Pyruvic Acid, Blood
Reporting Name
Pyruvic Acid, BUseful 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
Testing Algorithm
See Epilepsy: Unexplained Refractory and/or Familial Testing Algorithm
Method Name
Spectrophotometry (SP)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Whole bloodAdditional Testing Requirements
This test does not calculate the lactate:pyruvate ratio. To obtain this information, both this test and LACS1 / Lactate, Plasma must be ordered. The ratio can be calculated from the results obtained from these tests. A separate specimen must be obtained for lactate testing, see LACS1 / Lactate, Plasma.
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. Taking care to not spill any of the preservative, cautiously remove the cap from the tube.
4. Immediately transfer blood, once drawn, to the prechilled, special collection tube, recap, and shake vigorously to mix.
Additional Information:
1. Check expiration date before using. Supplied collection tube expires 14 months after preparation.
2. If perchloric acid (preservative) spills, obtain a new, prechilled tube.
Specimen Minimum Volume
See Specimen Required
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole blood | Refrigerated | 15 days | PYRUVATE |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
Special Instructions
Reference Values
0.08-0.16 mmol/L
NIH Unit
0.7-1.4 mg/dL
Day(s) Performed
Monday, Wednesday
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 |
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.
Cautions
Correct specimen collection and handling is crucial to achieve reliable results.
Pyruvic acid levels alone have little clinical utility. Abnormal concentrations of pyruvic acid and lactate-to-pyruvate (L:P) ratios are not diagnostic for a particular disorder but must be interpreted in the context of the patient's clinical presentation and other laboratory studies. The determination of pyruvic acid is of diagnostic value when lactic acid is measured and the L:P ratio is established in the same specimen.
When comparing blood and cerebrospinal fluid (CSF) L:P ratios, blood and CSF specimens should be collected at the same time.
Method Description
Pyruvate, in the presence of excess nicotinamide adenine dinucleotide, hydrogen ions, and lactic dehydrogenase is reduced to lactate. The reaction is stoichiometric; the decrease in absorbance at 340 nm is directly proportional to the concentration of pyruvate.(Fleischer WR, Forman DT, Huckabee WE, Antonis A, Young K. Enzymatic methods for lactic and pyruvic acids. In: MacDonald RP, ed. Standard Methods of Clinical Chemistry. Vol 6. 1970:245-259; Huckabee WE. Relationships of pyruvate and lactate during anaerobic metabolism. I. Effects of infusion of pyruvate or glucose and of hyperventilation. J Clin Invest. 1958;37:244-254; Cowan T, Pasquali M. Laboratory investigations of inborn errors of metabolism. In: Sarafoglou K, Hoffman GF, Roth KS, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. McGraw-Hill; 2017:1139-1158)
Report Available
2 to 5 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.Genetics Test Information
The lactate:pyruvate (L:P) ratio is considered a helpful (not diagnostic) tool in the evaluation of patients with possible disorders of mitochondrial metabolism, especially in patients with neurologic dysfunction and either elevated or normal blood lactate levels. Pyruvic acid levels alone have little clinical utility.