Originally published in CAP TODAY
Stephen J. Sarewitz, MD
From the files of the CAP's checklist-related questions. Answers by Stephen
J. Sarewitz, MD, LAP checklist commissioner and staff pathologist, Valley Medical
Center, Renton, Wash.
Q. What materials are acceptable for validating new lots of reagent?
A. We continue to receive on a regular basis questions
regarding reagent lot validation and the materials that should be used. The
following checklist questions address this topic.
- CHM.12900: Are new reagent lots validated before or concurrent with use
for patient testing?
- MIC.21620 and IMM.33150: Are new reagent lots checked against old reagent
lots or with suitable reference material before or concurrently with being
placed in service?
New lots of reagent must be tested in parallel with old lots before or concurrently with being placed in service. This ensures that the new lot of reagent does not affect the performance of the test method. Retained patient samples are ideal for validating new reagent lots since it is patient specimens that are being tested.
For clinical chemistry tests, other materials are acceptable, including reference materials provided by the method manufacturer specifically for the method being validated and proficiency testing materials with peer group-established values. Quality control material may also be used, but the laboratory must be aware of the possibility of matrix interference with such materials. That is, these materials may not respond to the reagent lot change in the same way as patient specimens. Therefore, a new reagent lot could alter the calibration of the method and change patient results, while the quality control cross-checking might not reflect this alteration. When a problem with patient results is suspected after a new reagent lot has been validated with QC material, the laboratory should consider re-evaluating the calibration status of the method.
For validation of new lots of reagent for qualitative tests used in microbiology and immunology, the new lot should be cross-checked with a positive and negative specimen. If results are reported as "weakly positive," then a weakly positive sample should be used for validation. Again, retained patient specimens are ideal, although for some tests, such as antigen-detection tests, some specimens are unstable, and positives are infrequent. In such cases, external reference or QC materials should be used.
Q. Checklist question GEN. 40522 requires annual training for the shipping of infectious materials. The International Air Transport Association and U.S. Department of Transportation require certified training every two and three years, respectively. So why does the College require annual training?
A. In the next edition of the CAP's laboratory general checklist, slated for release in December, the word "annual" will be removed from checklist item GEN.40522 for the aforementioned reasons. The question will read: Is there documented certified training of all personnel involved in the packaging and shipping of infectious materials?
The International Air Transport Association requires that people who ship dangerous
materials, including diagnostic specimens, infectious substances, and biological
toxins, be trained appropriately. Training materials are available from professional
organizations, such as IATA and the American Society for Microbiology, as well
as suppliers of packaging materials for dangerous goods, state health departments,
and the Centers for Disease Control and Prevention's National Laboratory Training
Network. A search of the Web will reveal multiple sources for certified training.
Laboratories can send personnel to an outside training course or conduct their
own training in-house. The training must, however, offer:
- Explanations of IATA and DOT regulations.
- Detailed instructions on packaging, labeling, and documentation.
- Safety training, specifically about the hazards of the materials and emergency
Employees are considered trained only when they earn certification. "Certified" training means that the employer must create a written record of training that states that the employee is trained to the satisfaction of the employer. The record must include the employee's name, date of training, description or copy of the training process, location of training, name and address of the trainer, and a statement of certification.