What is the best course of action if a technologist needs to perform a stat ionized calcium assay but the serum is older than three hours?

The best course of action is to request a new sample if the serum is older than three hours before performing a stat ionized calcium assay. This is crucial because ionized calcium levels can change significantly over time due to metabolic processes and sample handling. Serum samples that are not analyzed promptly may undergo changes such as shifts in pH that can affect the accuracy of the ionized calcium measurement.

In this case, requesting a new sample ensures that the assay results reflect the patient's current metabolic state accurately. Delays in processing can lead to misleading results, which could potentially impact patient care decisions. Timely and appropriate handling of specimens is essential in clinical chemistry to ensure the reliability of test outcomes.