Laboratory Quality Assurance - Proficiency Testing

Proficiency Testing

Proficiency testing (PT), mandated by Clinical Laboratory Improvement Amendments (CLIA) '88, is a source of external quality control. This practice of testing unknown specimens from an outside source provides an additional means to assure quality laboratory testing results. Although laboratories perform daily internal quality control with their test systems, external quality control provides important interlaboratory comparisons to determine the accuracy and reliability of the testing procedures.

For laboratories applying for an initial Medical Test Site (MTS) license (non-waived or non-PPMP categories), proof of enrollment in an approved PT program must be submitted to LQA before the MTS license can be issued.

For more information see our frequently asked questions page or browse the information in the drop downs below.

Approved Proficiency Testing Providers

Proficiency testing providers approved by the Centers for Medicare and Medicaid Services:

Accutest, 800-665-2575

American Academy Of Family Physicians, 800-274-7911

American Association of Bioanalysts, 800-234-5315

American Proficiency Institute, 800-333-0958

ACP Medical Laboratory Evaluation, 800-338-2746

College of American Pathologists, 800-323-4040

EXCEL (CAP), 800-323-4040

WSLH, 800-462-5261

Enrollment Requirements

Except where there is no available Proficiency Testing (PT) program or PT is not required, each Medical Test Site (MTS) shall demonstrate satisfactory participation in a Federal Health and Human Services Centers for Medicare and Medicaid Services (CMS) approved PT program, appropriate for the tests performed on-site, excluding waived tests. (Note: Bacteriology, Mycology, Mycobacteriology: these subspecialties do not have "regulated analytes" per se. However, the laboratory must subscribe to a module that covers the testing performed.) The MTS must enroll each year. If the MTS is currently enrolled in an approved PT program, the provider will automatically send a renewal form for the next year in the fall of the year.

For non-regulated analytes or tests for which there is no PT available, the MTS must have a system for biannual verification of the accuracy of its test results. This may be accomplished by analyzing specimens from a PT company or reference laboratory, by comparing split samples with a reference laboratory, by performing patient correlation, etc. At least two specimens should be used for test verification every six months.

Laboratory Quality Assurance will monitor performance throughout the year for regulated analytes. During the on-site survey, unregulated/ungraded tests will be reviewed to see if: (1) laboratory is reviewing PT results for these tests; (2) any problems have been noted by the laboratory; and, (3) corrective action has been taken when indicated. The laboratory may be cited if it is not reviewing the unregulated/ungraded tests and/or has not taken appropriate corrective action when problems are noted.

Performance Requirements

Number of Challenges: The Proficiency Testing (PT) programs are required to provide a minimum of five samples per testing event, with three testing events per year.

Minimum acceptable score for satisfactory participation:

  • Microbiology, General Immunology, Syphilis Serology, Routine Chemistry, Endocrinology, Toxicology and Hematology:
    • Eighty percent overall testing event score for all specialties
    • Eighty percent for each analyte
    • One hundred percent for HIV testing
  • Immunohematology:
    • One hundred percent for each analyte and overall testing event score for ABO (test used to type blood – either A, B, or O) group and D(Rho) typing
    • One hundred percent overall testing event score for compatibility testing
    • Eighty percent overall testing event score for Unexpected Antibody Detection and Antibody Identification

Unsatisfactory Performance

  • Unsatisfactory analyte score;
  • Unsatisfactory PT event or overall score for a specialty or subspecialty;
  • Failure to participate in a testing event; or
  • Failure to return PT results within specified timeframe.

Unsuccessful Participation

Failure to achieve satisfactory performance (overall testing event score or analyte score, where applicable) for two consecutive testing events or two out of three consecutive events.

Actions to Be Taken by LQA and MTS for Unsuccessful Participation

  1. Laboratory Quality Assurance (LQA) staff will send the Medical Test Site (MTS) a certified letter identifying the problem and stating that the laboratory may choose to discontinue patient testing for the identified test, specialty or subspecialty or follow a directed plan of correction (options listed in the letter).
  2. The MTS shall notify LQA, in writing, within 15 days of receipt of the notice, of the decision to discontinue testing patient specimens for the identified test, subspecialty or specialty or to agree to a directed plan of correction. If a laboratory fails to respond within fifteen days, LQA will notify the laboratory by letter, or by phone, that its response is overdue. When the response is received, LQA will review the response and, if acceptable, notify the laboratory that its request has been accepted. If the plan is unacceptable, LQA will contact the laboratory to discuss obtaining an acceptable response. If no response is received within five days of the receipt of the letter/phone call, appropriate disciplinary action will be initiated
  3. If the MTS chooses to discontinue patient testing for the identified test, the director may petition for reinstatement after satisfactory performance in two successive events.
  4. The department shall notify the MTS in writing, within 15 days of receipt of the petition, of its decision related to reinstatement.

Directed Plan of Correction

If a laboratory has failed two consecutive testing events or two out of three consecutive events of PT, LQA may give the laboratory options rather than require it to discontinue patient testing. These options may be any one or a combination of the following:

  1. Undertake appropriate training for the testing personnel involved;
  2. Employ technical assistance necessary to correct PT problem; or
  3. Perform special studies such as:
    • Testing 10 or more patient specimens from its reference laboratory; or
    • Obtaining and analyzing additional PT material from a PT agency.

NOTE: For special studies, the laboratory must submit the results and a statistical analysis of the results to LQA. LQA will review the data to determine if the laboratory has performed satisfactorily on the special study.

When LQA determines that the MTS has successfully completed its directed plan of correction, a letter will be sent stating that LQA accepts the results and the laboratory may continue testing patient specimens for the analyte(s). The letter will also inform the laboratory that if it receives an unsatisfactory grade on either of the next two sets of PT, it will have to discontinue testing until it passes two consecutive sets of PT.

If a laboratory fails to respond within 15 days, LQA will notify the laboratory by letter that its response is overdue. If no response is received within five days of the receipt of the letter, appropriate disciplinary action will be initiated.

A laboratory may be offered a directed plan of correction only once for an analyte(s). If there is a failure in either of the next two events for the same analyte, the MTS will be required to discontinue patient testing until it successfully passes two consecutive sets of PT for that analyte.

If it is discovered during an on-site survey that a laboratory has not enrolled in an approved PT program, a deficiency will be written. The only acceptable plan of correction (POC) is immediate enrollment in PT with proof of enrollment sent along with the POC.

Disciplinary Action

If a laboratory refuses to voluntarily discontinue testing patient specimens when it has been notified to do so, or does not respond in writing to the notification, LQA will begin enforcement action.

Proficiency Testing Monitoring

The Office of Laboratory Quality Assurance (LQA) monitors proficiency testing (PT) performance according to the Clinical Laboratory Improvement Amendments (CLIA) requirements for PT.

Laboratories must authorize their proficiency testing company to release their PT results to Laboratory Quality Assurance for monitoring. This is done at the time of enrollment in the PT program for the current year. If the PT company does not send copies of PT results to LQA for monitoring, the laboratory will receive an unsatisfactory grade for non-participation and may jeopardize the facility's Medical Test Site license. LQA will notify the federal Health and Human Services Centers for Medicare & Medicaid Services (CMS) of any adverse actions relating to PT; this information will be published by CMS in its annual Laboratory Registry Report.

Regulated Analytes

Listed below are current regulated analytes as defined by the Centers for Disease Control and Prevention.

These tests must be covered by Proficiency Testing.




Alkaline phosphatase



Bilirubin, total (or neonatal)

Blood gas pO2, pCO2, pH

Calcium, total


Cholesterol, total HDL


Creatine kinase

Creatine kinase isoenzymes



Iron, total


LDH isoenzymes




Total Protein


Urea Nitrogen

Uric Acid



Free Thyroxine

Serum Pregnancy (HCG)
(qualitative or quantitative)

T3 Uptake






Alcohol, blood

Blood lead













Valproic Acid


Cell Identification

Auto/manual WBC differential

Erythrocyte Count (RBC)

Hematocrit (automated)


Leukocyte count (WBC)

Platelet Count


Partial thromboplastin time

Prothrombin time


ABO Group

D (Rh typing)

Antibody Detection

Compatibility testing

Antibody Identification

Syphilis Serology




Alpha-1 antitrypsin

AFP (tumor marker)

Antinuclear antibody



Complement C3, C4

HBsAg, Anti-HBc, HBeAg

IgA, IgE, IgG, IgM

Infectious mononucleosis

Rheumatoid factor



Cover the Specialty according to the different types of testing performed


Cover the Specialty according to the different types of testing performed


Direct only




Culture or FA

Other EIA for virus


Over the Specialty according to the different types of testing performed