Total Carbon Dioxide Measured by the Vitros Enzymatic Method
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Annarita Frezzotti
Abstract
We evaluated the performance of an enzymatic method using dry chemistry for serum total carbon dioxide (tCO2) determination using a Vitros 500 analyser. Imprecision results were acceptable and the linearity was verified for concentrations within a range of 5.5–39.2 mmol/l, i.e. ymeasured = 0.93 xcalculated +1.32, r = 0.99. The Vitros tCO2 method was unaffected by haemoglobin at all concentrations tested. Significant interference was caused by bilirubin at concentrations higher than 30 μmol/l; the addition of bilirubin lowered the apparent values for tCO2 dose-dependently. Serum tCO2 results were practically the same as those for plasma. The reference interval for venous tCO2 concentrations in a healthy population was: 22.4–34.2 mmol/l (mean: 28.3 mmol/l). Comparison of venous serum tCO2 results assayed using the Vitros method with bicarbonate (HCO3−) values calculated by blood gas determination of pCO2 and pH in arterial blood samples gave poor agreement, r = 0.58. The data revealed a mean difference of 5.48 ± 3.09 mmol/l between the tCO2 measurements and calculated bicarbonate. This was statistically (p = 0.01) and clinically significant. We conclude that the Vitros method provides reliable tCO2 results in venous serum but this method must not be used as an interchangeable alternative to calculated arterial bicarbonate in order to avoid confusion, misinterpretation of results and erroneous therapeutic decisions.
Copyright © 1998 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- Editorial
- Predictive Medicine
- Standardization and Clinical Management of Lipoprotein(a) Measurements
- Evaluation of the Iron Status of the Newborn by Soluble Transferrin Receptors in Serum
- Quantitation of IgG and IgM Human Anti-Mouse Antibodies (HAMA) Interference in CA 125 Measurements Using Affinity Chromatography
- Neopterin Plasma Concentrations Predict the Course of Severe Acute Pancreatitis
- Objectives, Design and Recruitment of a Familial and Longitudinal Cohort for Studying Gene-Environment Interactions in the Field of Cardiovascular Risk: The Stanislas Cohort
- Total Carbon Dioxide Measured by the Vitros Enzymatic Method
- Evaluation of Glucocard Memory 2 and Accutrend® Sensor Blood Glucose Meters
- Evaluation of Circulating Type I Procollagen Propeptides in Patients with Paget's Disease of Bone
- Properties and Units in the Clinical Laboratory Sciences XIII. Properties and Units in Reproduction and Fertility
- Procalcitonin as a Specific Marker of Bacterial Infection in Adults
- Biological Variation and Quantification of Health: The Emergence of the Concept of Normality
