What is the most common method for measuring potassium levels in the lab?

The most common method for measuring potassium levels in the laboratory is through the use of ion-selective electrodes. This method is highly favored because ion-selective electrodes are specifically designed to measure the concentration of ions in solution with a high degree of specificity and sensitivity.

Ion-selective electrodes operate based on the Nernst equation, which relates voltage to ion concentration. When a sample is analyzed, the electrode generates a potential difference that corresponds to the activity or concentration of potassium ions in that sample. This technique is quick, requires minimal sample preparation, and can be performed on small volumes of serum or plasma, making it practical for routine clinical use.

In addition to its practicality, the ion-selective electrode method provides instantaneous results, which is crucial in clinical settings where timely decisions about patient care are necessary. Given these advantages, it is the preferred choice for measuring potassium levels, especially compared to alternative methods such as titrations, which may not be as direct or efficient for ion concentration measurement in biological fluids.