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Bicarbonate (CO2)

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EPIC Test Name

CO2 LEVEL, TOTAL

EPIC Code

LAB55

Specimen Requirements

plasma
Minimum Volume:0.5 mL
Collection:Collect specimens using standard laboratory procedures.
Transport:Room Temperature ASAP
Stability:Room Temperature: 40 hours at 15-25 degrees C
Refrigerated: 7 days at 2-8 degrees C (tightly capped)
Frozen: 6 months at -20 to -80 degrees C
Container:LT GRN
Rejection Causes:Hemolysis,
Insufficient Sample Volume

Methods

Spectrophotometric assay using phosphoenolpyruvate in the presence of PEPC

Turnaround Time

SpecimenTurnaround TimeFrequency
plasmaStat: 90 minutes Routine: 4 hours24/7

Reference Ranges

Spectrophotometric assay using phosphoenolpyruvate in the presence of PEPC
AgeAll RangeUnitCritical Values
0 days up to 29 days22-29 mmol/Lmmol/L<15 and >35 mmol/L
29 days up to 999 days22-29 mmol/L<10 and >40 mmol/L

Clinical Indications

Bicarbonate is the second largest fraction of the anions in plasma after CL-. It includes bicarbonate (HCO3-) and carbonate (CO32-) ions, as well as the carbamino compounds. At the physiological pH, the concentration of carbonate is 1/1000 that of bicarbonate. The carbamino compounds exist in such low quantities that they are generally not mentioned specifically.
The bicarbonate content of serum/plasma is used as an indicator of electrolyte dispersion and anion deficit. Together with pH, bicarbonate concentrations are used in the diagnosis and treatment of numerous potentially serious disorders associated with acid‑base imbalance in the respiratory and metabolic systems. Some of these conditions are diarrhea, renal tubular acidosis, renal failure, carbonic anhydrase inhibitors, hyperkalemic acidosis, and diabetic ketoacidosis.

Additional Information

Determination of bicarbonate (HCO3) actually includes dissolved carbon dioxide (CO2). CO2 can diffuse from the sample into the air due high partial pressure once the vacutainer tube is opened. This may change in the measured bicarbonate concentration in the sample by a rate of about 6 mmol/L per hour. The sample tube opening time should be kept minimal as possible.

Common Synonyms

TCO2

Performed

Lab
Chemistry - Community
Chemistry - Downtown
Verona Cancer Center

Interpretative Information

Values of bicarbonate (HCO3) and carbon dioxide (CO2) above or below reference ranges indicate an acid-base imbalance. However, the nature of the acid-base imbalance cannot be determined based on the bicarbonate value alone. Its value has significance in the context of other electrolytes, such as pH and pCO2.

CPT

82374

LOINC

1963-8

References

Shindler E, Brown SM, Scott M. Electrolytes and Blood Gases. In Tietz Textbook of Clinical Chemistry. Edited by N Rifai, AR Norwath and C Wittwer, 6 ed. St. Louis, Missouri, Elsevirer Inc, 2018, pp 604-625. ISBN: 978-0-323-35921-4

Contact Information

Chemistry - Downtown: (315)464-4460
Chemistry - Community: (315)492-5531
Verona Cancer Center: (315)473-3859
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