Kathleen P. Freeman

ASVCP guidelines: allowable total error guidelines for biochemistry

As all laboratory equipment ages and contains components that may degrade with time, initial and periodically scheduled performance assessment is required to verify accurate and precise results over the life of the instrument. As veterinary patients may present to general practitioners and then to referral hospitals (both of which may each perform in-clinic laboratory analyses using different instruments), and given that general practitioners may send samples to reference laboratories, there is a need for comparability of results across instruments and methods. Allowable total error (TEa ) is a simple comparative quality concept used to define acceptable analytical performance. These guidelines are recommendations for determination and interpretation of TEa for commonly measured biochemical analytes in cats, dogs, and horses for equipment commonly used in veterinary diagnostic medicine. TEa values recommended herein are aimed at all veterinary settings, both private in-clinic laboratories using point-of-care analyzers and larger reference laboratories using more complex equipment. They represent the largest TEa possible without generating laboratory variation that would impact clinical decision making. TEa can be used for (1) assessment of an individual instruments analytical performance, which is of benefit if one uses this information during instrument selection or assessment of in-clinic instrument performance, (2) Quality Control validation, and (3) as a measure of agreement or comparability of results from different laboratories (eg, between the in-clinic analyzer and the reference laboratory). These guidelines define a straightforward approach to assessment of instrument analytical performance.

ASVCP quality assurance guidelines: control of preanalytical and analytical factors for hematology for mammalian and nonmammalian species, hemostasis, and crossmatching in veterinary laboratories.

In December 2009, the American Society for Veterinary Clinical Pathology (ASVCP) Quality Assurance and Laboratory Standards committee published the updated and peer-reviewed ASVCP Quality Assurance Guidelines on the Societys website. These guidelines are intended for use by veterinary diagnostic laboratories and veterinary research laboratories that are not covered by the US Food and Drug Administration Good Laboratory Practice standards (Code of Federal Regulations Title 21, Chapter 58). The guidelines have been divided into 3 reports: (1) general analytical factors for veterinary laboratory performance and comparisons; (2) hematology, hemostasis, and crossmatching; and (3) clinical chemistry, cytology, and urinalysis. This particular report is one of 3 reports and provides recommendations for control of preanalytical and analytical factors related to hematology for mammalian and nonmammalian species, hemostasis testing, and crossmatching and is adapted from sections 1.1 and 2.3 (mammalian hematology), 1.2 and 2.4 (nonmammalian hematology), 1.5 and 2.7 (hemostasis testing), and 1.6 and 2.8 (crossmatching) of the complete guidelines. These guidelines are not intended to be all-inclusive; rather, they provide minimal guidelines for quality assurance and quality control for veterinary laboratory testing and a basis for laboratories to assess their current practices, determine areas for improvement, and guide continuing professional development and education efforts.

ASVCP guidelines: quality assurance for point-of-care testing in veterinary medicine

Point-of-care testing (POCT) refers to any laboratory testing performed outside the conventional reference laboratory and implies close proximity to patients. Instrumental POCT systems consist of small, handheld or benchtop analyzers. These have potential utility in many veterinary settings, including private clinics, academic veterinary medical centers, the community (eg, remote area veterinary medical teams), and for research applications in academia, government, and industry. Concern about the quality of veterinary in-clinic testing has been expressed in published veterinary literature; however, little guidance focusing on POCT is available. Recognizing this void, the ASVCP formed a subcommittee in 2009 charged with developing quality assurance (QA) guidelines for veterinary POCT. Guidelines were developed through literature review and a consensus process. Major recommendations include (1) taking a formalized approach to POCT within the facility, (2) use of written policies, standard operating procedures, forms, and logs, (3) operator training, including periodic assessment of skills, (4) assessment of instrument analytical performance and use of both statistical quality control and external quality assessment programs, (5) use of properly established or validated reference intervals, (6) and ensuring accurate patient results reporting. Where possible, given instrument analytical performance, use of a validated 13s control rule for interpretation of control data is recommended. These guidelines are aimed at veterinarians and veterinary technicians seeking to improve management of POCT in their clinical or research setting, and address QA of small chemistry and hematology instruments. These guidelines are not intended to be all-inclusive; rather, they provide a minimum standard for maintenance of POCT instruments in the veterinary setting.

Biological variation and reference change values of feline plasma biochemistry analytes

This is the first report concerning biological variation and reference change values of feline plasma biochemistry components in the peer-reviewed literature. Biological variation refers to inherent physiological variation of analytes. The ratio of individual biological variation to group biological variation is referred to as an analyte’s index of individuality. This index determines the suitability of an analyte to be assessed in relation to population- or subject-based reference intervals. A subject-based reference interval is referred to as a reference change value or critical difference, and is calculated from individual biological variation. Fourteen cats were sampled for plasma biochemistry analysis once weekly for 6 weeks. Samples were stored and then tested at the same time. Results were assessed in duplicate and coefficients of variation for each analyte were isolated to distinguish variation within each subject, between all subjects and by the analyser. From these results, an index of individuality and reference change values were determined for each analyte. Five plasma biochemistry analytes (alkaline phosphatase, alanine aminotransferase, cholesterol, creatinine and globulin) had high individuality and, therefore, subject-based reference intervals are more appropriate; only one analyte (sodium) had low individuality, indicating that population-based reference intervals are appropriate. Most analytes had intermediate individuality so population-based reference intervals should be assessed in relation to subject-based reference intervals. The results of this study demonstrate high individuality for most analytes and, therefore, that population-based reference intervals are of limited utility for most biochemical analytes in cats.

Cholelithiasis and hyperthyroidism in a cat

A 14-year-old domestic short-hair cat presented with a history of intermittent malaise and increased drinking. A diagnosis of hyperthyroidism and cholelithiasis was made by a combination of blood testing, radiography and ultrasonography. After medical management of hyperthyroidism, thyroidectomy and cholecystectomy were successfully performed. Removed choleliths were comprised of calcium carbonate and bilirubinate. Histopathological analysis of tissue suggested low grade pancreatic and hepatobiliary disease, as well as hyperthyroidism, might have contributed to stone formation.

ASVCP quality assurance guidelines: external quality assessment and comparative testing for reference and in‐clinic laboratories

The purpose of this document is to educate providers of veterinary laboratory diagnostic testing in any setting about comparative testing. These guidelines will define, explain, and illustrate the importance of a multi-faceted laboratory quality management program which includes comparative testing. The guidelines will provide suggestions for implementation of such testing, including which samples should be tested, frequency of testing, and recommendations for result interpretation. Examples and a list of vendors and manufacturers supplying control materials and services to veterinary laboratories are also included.

An error management system in a veterinary clinical laboratory

Error recording and management is an integral part of a clinical laboratory quality management system. Analysis and review of recorded errors lead to corrective and preventive actions through modification of existing processes and, ultimately, to quality improvement. Laboratory errors can be divided into preanalytical, analytical, and postanalytical errors depending on where in the laboratory cycle the errors occur. The purpose of the current report is to introduce an error management system in use in a veterinary diagnostic laboratory as well as to examine the amount and types of error recorded during the 8-year period from 2003 to 2010. Annual error reports generated during this period by the error recording system were reviewed, and annual error rates were calculated. In addition, errors were divided into preanalytical, analytical, postanalytical, and “other” categories, and their frequency was examined. Data were further compared to that available from human diagnostic laboratories. Finally, sigma metrics were calculated for the various error categories. Annual error rates per total number of samples ranged from 1.3% in 2003 to 0.7% in 2010. Preanalytical errors ranged from 52% to 77%, analytical from 4% to 14%, postanalytical from 9% to 21%, and other error from 6% to 19% of total errors. Sigma metrics ranged from 4.1 to 4.7. All data were comparable to that reported in human clinical laboratories. The incremental annual reduction of error shows that use of an error management system led to quality improvement.

Cytologic, histologic, and immunohistochemical features of lingual liposarcoma in a dog

A 9-year-old female spayed mixed-breed dog was presented to the referring veterinarian with a history of decreased appetite and difficulty with prehension and swallowing because of a firm oval mass in the tongue. On cytologic evaluation of a fine-needle aspirate of the mass there were numerous round to polygonal cells organized individually or in loose clusters with rare branching capillaries. The cells had eosinophilic granular cytoplasm, round to oval nuclei, and occasionally indistinct borders. The cytologic diagnosis was granular cell tumor (GCT) of the tongue. Impression smears of a biopsy sample of the lingual mass contained similar eosinophilic granular cells with variable numbers of clear vacuoles in the background, numerous perivascular arrangements, and occasional lipoblasts, suggestive of liposarcoma. On histologic examination the tumor was composed of numerous lipocytes with rare foci of round eosinophilic granular cells without evidence of vacuolation; occasionally, atypical mitotic figures were seen. Immunohistochemically, the cells were uniformly negative for periodic acid-Schiff and did not express smooth muscle actin, desmin, or cytokeratin but were immunoreactive for vimentin and S100. A diagnosis of well-differentiated liposarcoma was made on the basis of morphologic and immunohistochemical results. Eosinophilic granular cells may be a component of well-differentiated liposarcoma and are not limited to GCT. Liposarcoma should be considered in the differential diagnoses of lingual tumors in the dog when cytological evaluation reveals eosinophilic granular cells consistent with GCT.

Quality documentation challenges for veterinary clinical pathology laboratories

An increasing number of veterinary laboratories worldwide have obtained or are seeking certification based on international standards, such as the International Organization for Standardization/International Electrotechnical Commission 17025. Compliance with any certification standard or quality management system requires quality documentation, an activity that may present several unique challenges in the case of veterinary laboratories. Research specifically addressing quality documentation is conspicuously absent in the veterinary literature. This article provides an overview of the quality system documentation needed to comply with a quality management system with an emphasis on preparing written standard operating procedures specific for veterinary laboratories. In addition, the quality documentation challenges that are unique to veterinary clinical pathology laboratories are critically evaluated against the existing quality standards and discussed with respect to possible solutions and/or recommended courses of action. Documentation challenges include the establishment of quality requirements for veterinary tests, the use or modification of human analytic methods for animal samples, the limited availability of quality control materials satisfactory for veterinary clinical pathology laboratories, the limited availability of veterinary proficiency programs, and the complications in establishing species-specific reference intervals.

Establishment of canine hematology reference intervals for the Sysmex XT-2000iV hematology analyzer using a blood donor database

BACKGROUND The Sysmex XT-2000iV is a hematology analyzer that combines impedance and optical techniques and has been previously validated for dogs. Specific reference intervals (RIs) are useful when interpreting results. OBJECTIVES The aim of this study was to determine hematologic RIs for the Sysmex XT-2000iV using a large reference population of client-owned clinically healthy blood donor dogs, adopting an indirect sampling method. METHODS Dogs were screened for breed, size, health, travel history, and previous blood transfusions, and the quality of blood specimens was also reviewed. Results from specimens that met inclusion criteria were used to determine RIs using a nonparametric method. Specimens from Akitas and sighthounds were excluded from the study. RESULTS Of 992 specimens that had been collected from blood donors and analyzed, 297 were initially included in the RI study. An additional 38 specimens were excluded as outliers, and hematologic RIs for the Sysmex XT-2000iV were based on analysis of specimens from 259 clinically healthy dogs. Measurands evaluated had variable distributions, and intervals obtained were generally comparable to previously reported RIs. Differences observed included higher lower and upper reference limits (LRL and URL, respectively) for MCV and lower URL for WBC count. Reticulocyte count and the LRL of the absolute lymphocyte count were also higher than previously reported, and the RI for platelet count was narrower and lower. CONCLUSIONS Canine RIs for the Sysmex hematology analyzer were established using an indirect sampling method with reference individuals selected from a large database of client-owned clinically healthy blood donor dogs. For specimens included in this study, time from collection to analysis was similar to what veterinary commercial laboratories experience.