From the Research
If a blood sample for a Comprehensive Metabolic Panel (CMP) test is collected with the wrong anticoagulant or tube type, such as EDTA, the sample should be rejected and a new specimen should be collected using the correct tube, as incorrect tubes can significantly interfere with test results, altering electrolyte levels and other analytes. When collecting a blood sample for CMP testing, it is crucial to use the correct tube type to ensure accurate results. The recommended tube types for CMP testing are gold/yellow-top serum separator tubes (SST) or red-top tubes without anticoagulants 1. Using the wrong tube, such as those containing EDTA (purple-top), can lead to inaccurate results, as EDTA can chelate calcium and falsely lower calcium results. Key considerations for proper specimen collection include:
- Proper patient identification
- Using the correct tube type
- Filling the tube adequately
- Inverting the tube gently 5-8 times to mix any additives
- Transporting the sample to the laboratory promptly As highlighted in a recent study published in the Scandinavian journal of clinical and laboratory investigation 1, proper blood collection and timely analysis are vital steps for reliable results, and the use of incorrect tubes can lead to clinically significant alterations in electrolyte concentrations. Therefore, it is essential to reject the sample and recollect it using the correct tube type to ensure accurate CMP results, which are critical for clinical decisions regarding kidney function, liver function, electrolyte balance, and metabolic status.