Username: Password:

Proficiency Laboratory Medicine Improve Your PT Performance

How to Improve Your PT Performance

Proficiency testing is one way a laboratory can assess the quality of its work and by utilizing this tool properly can lead to improvement of performance over time. Laboratories compare their results with their closest peers in methodology and instrumentation and gather useful information regarding their deviation from the group mean, imprecision and trending biases. By careful examination of these results, laboratories can continuously work to improve their level of performance.


Troubleshooting Tips

» Review reports from PT providers carefully. These reports contain useful information beyond the pass or fail grade. They may identify potential problems related to imprecision, systematic error and / or human error.

» Determine whether a significant number of laboratories were failed or eliminated for varying results. Follow-up with the PT program provider.

» Use the “Investigation and Exception Response Form” to help find the ‘root cause’ of any unexpected results. 

» Look for trends over time. Are all PT samples showing a negative or positive bias? Is there a bias at certain analyte concentrations? These events should trigger internal investigations.

» Review your quality control records, looking for warning shifts and trends in the test method.

» Check reconstitution, expiration and reconstituted stability on QC, reagents, calibrators, stains and solutions.

» Review last calibration of the test procedure.

» Review the test method protocol and procedures.

» Ensure instrumentation / methodology is current with updated software, revised procedures or updated control range.


PT program providers offer technical assistance to participating laboratories. Manufacturers have an interest in customers performing well on PT testing and should be consulted as required.



Additional Tips for Better PT Results

  • Monitor PT shipping schedules and notify manufacturer when delay in receiving samples has occurred. 
  • Open PT shipment as soon as it is received. Check for broken and leaking vials. If samples are warm, frozen or liquid materials may be compromised and subsequently have problems with various analytes including enzymes and hormones. Consult with the PT vendor as materials may need to be replaced.
  • Staff should be up to date on the written policies of the laboratory in regards to calibration, linearity checks and test method choices.
  • Staff should be trained in the proper handing of PT samples, results and reports.
  • Analyzers should be maintained and functioning properly.
  • Follow the manufacturer’s instructions carefully in regards to reconstitution:
    • Correct assay vial
    • Correct diluent and amount of diluent
    • If water is the diluent, use reagent grade water
    • Use calibrated pipettes to deliver diluent
    • Allow sufficient time for equilibration and use correct equilibration conditions (do not use water baths, shakers, rockers etc. unless specified in the provider’s instructions)
  • For liquid PT samples, allow material to come to room temperature naturally or as specified by the provider.
  • Calibration and linearity checks are kept current. Recalibration is done when necessary.
  • Accuracy and precision should be established.
  • Ensure QC is always current, checked and properly maintaining your system.
  • Where applicable enroll in QC manufacturer’s peer group comparison programs. These comparisons may be more frequent and / or have a larger or more specific database than the PT program.
  • Where possible use multi-level QC materials and use multi-rule QC applications.
  • Clerical errors are common in PT reporting. If possible, get another tech to check data entry. As PT may fall outside the stream of normal LIS data transfer, be especially careful with clerical and transcription functions including:
    • Reporting correct sample
    • Rounding
    • Units
    • Decimal places
    • Conversion factor
  • Avoid waiting to the last minute to analyze samples in case of problems with instrument or method.
  • Return results to PT program provider before cutoff time / date. Note time zone differences.

»  If possible freeze left-over material for future confirmatory testing if necessary.

» Keep original instrument prints-outs and reporting forms for confirmation if necessary.

»  Take advantage of internet-based educational programs provided by some manufacturers.


Additional uses for left-over PT material

  • PT material may be used as a control or reference material in evaluating new or existing methods.
  • PT materials may be used for intra-method comparison and verification of secondary or back-up laboratory test systems.
  • PT materials may be used as internal evaluation samples.
  • PT materials may be used as unknowns for training or competency testing.
  • Color photographs and photomicrographs of PT materials may be used to enhance training
  • PT material may not be used to calibrate different testing systems or to assess their accuracy and validity in cases where test results may be affected by potential sample matrix issues of the PT samples.