Dear API Abby:

My hospital tests sodium in several different areas using different methods, but we all share a CLIA license.  I feel like testing each area is necessary, but my lab director says only one result is sent to CLIA.  Is this true and if so, how do we decide whose method is the most important?

Salty Decisions

Dear Salty:

In short, you’re both right. Your lab director is correct that only one sodium method is reported to your state CLIA office or accreditation agency as the regulated score for your CLIA number. But you’re also correct that each method needs to be monitored, validated, and included in your quality system.

Under CLIA, your laboratory is viewed as a single entity, so only one proficiency testing (PT) score per analyte can be submitted for the entire CLIA number. However, every testing site and every method used for patient care must still perform method comparisons, calibration verification, PT, or alternative assessments — and they must meet accuracy and precision requirements. So even though only one sodium score is officially submitted, all sodium methods must be evaluated and maintained to CLIA standards.

How do you decide which method is “most important”? Many laboratories choose the method that is the most analytically robust (best precision, least interference), or of the highest complexity. Others choose the method with the highest patient‑testing volume. In many hospitals, the core laboratory chemistry analyzer will be the method selected as “most important” for regulatory purposes rather than point‑of‑care devices, blood gas analyzers, or methods used in satellite labs. Whatever you choose, the decision should be intentional and documented as part of your laboratory’s quality management plan.

Even though CLIA only requires PT for one method, many laboratories use PT to monitor accuracy and reliability in other areas of the facility. This can be simpler than alternative assessment. It will not violate CLIA as long as different samples are used (for different technology, or from different PT providers). If your facility performs PT for sodium on more than one non-waived method, check with your PT provider(s) to ensure your chosen or “primary” method is the one reported for CLIA purposes.

Remember, just because CLIA only reviews one method’s PT scores in real time doesn’t mean the others escape scrutiny. Some accreditation agencies monitor all PT scores in real time. In addition, during your biennial inspection, surveyors will review PT and alternative assessment records for all methods. They will expect to see evidence that all sodium methods undergo some form of accuracy and reliability assessment. This ensures that every patient result, no matter where it’s generated, is trustworthy.

Dear API Abby:

I just started a new job where I oversee multiple sites that perform patient testing. Each site has the same model of analyzer to perform basic chemistry testing, and they all share the same CLIA license. How should proficiency testing be handled in this situation?  Should I be rotating amongst the sites?  Should one site be primary and the others do alternative assessments?  What is best practice?

So many sites, so little time

Dear So Many:

Congratulations on your new role and welcome to the world of multi-site testing, where CLIA gives you just enough flexibility to feel empowered…and enough responsibility to keep you humble.  The good news in this situation is that you truly do get to choose your own adventure.

When multiple sites with the same CLIA license have the same methodology, there are two main options for handling proficiency testing: designate one site as the primary PT site, or rotate PT among the sites. A third option is having all the sites perform PT from multiple providers to ensure samples are unique, but that is not very common.

Most multi-site laboratories use one PT program to meet PT enrollment requirements, and use alternative assessment to meet accuracy and reliability requirements for additional sites and equipment. Performing PT consistently at the same site is a clear choice if one site has the highest testing volume or tests more analytes. Regardless, other benefits of choosing either PT or alternative assessment for each site include streamlining workflows and recordkeeping, simplifying troubleshooting, and allowing you to identify better training needs. Consistent documentation for each site throughout the year also provides the clearest performance history for each site.  Importantly, it will give you the chance to identify a slowly developing trend before your quality control does; an important benefit of PT! With this approach, the sites not performing PT would instead perform alternative assessments using split sample analysis, linearity or calibration verification materials, retesting PT materials after the test event, or instrument-to-instrument comparisons within the same site.

On the other hand, rotating proficiency amongst the different sites may be effective if your test methods are less complex, if all sites use supplies such as cartridges or kits from a central storage location, or if the same staff rotate through all the sites. In this case, there are fewer variables specific to each site, so your PT is assessing the capability of your group as a whole. To implement this, you would need to assign each proficiency event to a different site. All sites will eventually get formally evaluated, though you need to document the rotation schedule and make sure that all analytes are covered for each test event. This approach requires tight coordination and clear communication so that PT samples are tested on time and by the correct site, and that other sites perform alternative assessments, as necessary.

No matter which path you choose, it’s essential to document thoroughly why you selected your approach, whether it’s based on testing volume, method complexity, staffing, or the analytes performed. You’ll also need a clear, structured plan outlining how each non‑primary site will complete its alternative assessments at least twice per year to demonstrate ongoing accuracy and reliability. Most importantly, you must ensure that any unacceptable results from PT or alternative assessment are addressed promptly. Strong documentation and consistent follow‑through will keep every site aligned and inspection‑ready.  

Please remember, you don’t have to navigate all of this alone. Multi‑site testing comes with a lot of moving parts, and even the most experienced leaders lean on their clinical consultants, quality specialists, PT program experts, and state CLIA office when questions come up. These teams are there to help and are excellent resources when you need clarification or guidance. Reaching out to these resources early and often will help you stay confident, compliant, and ahead of any surprises.