What should be done to obtain an accurate potassium (K+) level during a blood draw?

What should be done to obtain an accurate potassium (K+) level during a blood draw?

• A. Use a green top tube
• B. Obtain a serum sample
• C. Use an EDTA tube
• D. Request a venous blood gas

Answer: (B)

To obtain an accurate potassium (K+) level, it is essential to obtain a serum sample. Potassium levels are typically measured in serum rather than plasma, and using a serum sample helps ensure that the measurement reflects the potassium content accurately. Serum is the fluid component obtained after blood has clotted and the cells have been removed, providing a clear medium for analysis. When it comes to the other choices, while green top tubes (which typically contain heparin) can be used for plasma potassium measurements, they are less common for potassium assays; thus, the preference for serum samples remains strong in many clinical settings. Using an EDTA tube, which contains an anticoagulant, can affect potassium levels due to its binding properties, potentially leading to inaccurate results. Requesting a venous blood gas is unrelated to potassium testing directly and is usually performed for different purposes, such as assessing blood pH and carbon dioxide levels. Therefore, obtaining a serum sample is the most reliable method for accurately determining potassium levels in the laboratory.

To obtain an accurate potassium (K+) level, it is essential to obtain a serum sample. Potassium levels are typically measured in serum rather than plasma, and using a serum sample helps ensure that the measurement reflects the potassium content accurately. Serum is the fluid component obtained after blood has clotted and the cells have been removed, providing a clear medium for analysis.

When it comes to the other choices, while green top tubes (which typically contain heparin) can be used for plasma potassium measurements, they are less common for potassium assays; thus, the preference for serum samples remains strong in many clinical settings. Using an EDTA tube, which contains an anticoagulant, can affect potassium levels due to its binding properties, potentially leading to inaccurate results. Requesting a venous blood gas is unrelated to potassium testing directly and is usually performed for different purposes, such as assessing blood pH and carbon dioxide levels. Therefore, obtaining a serum sample is the most reliable method for accurately determining potassium levels in the laboratory.