Development of an Integrated Reporting System for Verifying Hemolysis, Icterus, and Lipemia in Clinical Chemistry Results

BACKGROUND: Hemolysis, icterus, and lipemia (HIL) cause preanalytical interference and vary unpredictably with different analytical equipments and measurement methods. We developed an integrated reporting system for verifying HIL status in order to identify the extent of interference by HIL on clinical chemistry results. METHODS: HIL interference data from 30 chemical analytes were provided by the manufacturers and were used to generate a table of clinically relevant interference values that indicated the extent of bias at specific index values (alert index values). The HIL results generated by the Vista 1500 system (Siemens Healthcare Diagnostics, USA), Advia 2400 system (Siemens Healthcare Diagnostics), and Modular DPE system (Roche Diagnostics, Switzerland) were analyzed and displayed on physicians' personal computers. RESULTS: Analytes 11 and 29 among the 30 chemical analytes were affected by interference due to hemolysis, when measured using the Vista and Modular systems, respectively. The hemolysis alert indices for the Vista and Modular systems were 0.1-25.8% and 0.1-64.7%, respectively. The alert indices for icterus and lipemia were <1.4% and 0.7% in the Vista system and 0.7% and 1.0% in the Modular system, respectively. CONCLUSIONS: The HIL alert index values for chemical analytes varied depending on the chemistry analyzer. This integrated HIL reporting system provides an effective screening tool for verifying specimen quality with regard to HIL and simplifies the laboratory workflow.

Artifactual Hyperbilirubinemia due to Paraprotein Interference in a Case of Multiple Myeloma / 임상검사와정도관리

When analyzing samples containing paraproteins, various interference effects are encountered in the clinical laboratory. Precipitation of paraproteins mostly interferes with the assays that use photometric detection. Herein, we present a case of a patient with multiple myeloma who had paraproteins and spuriously elevated total bilirubin levels (31.1 mg/dL), which were measured by using Roche total bilirubin assay on the Modular DPE (Roche Diagnostics, Switzerland) chemical analyzer. The total bilirubin concentration reduced from 31.1 mg/dL to 1.5 mg/dL, when tested after three fold dilution of the sample on Modular DPE chemical analyzer.

Comparison of Six Clinical Chemistry Test Results According to the Treatment of EDTA Anticoagulant in Body Fluid Specimens / 임상검사와정도관리

BACKGROUND: Specimen requirements such as type of anticoagulant and number of tube for body fluid analysis vary with specimen type and requested laboratory tests. We compared the results of six clinical chemistry tests between EDTA anticoagulated and anticoagulant-free body fluids. METHODS: A total of 191 body fluids (45 pleural, 28 bronchoalveolar lavage, 35 peritoneal, 45 peritosol, and 38 synovial fluids) were aliquoted into EDTA tubes and anticoagulant-free tubes, and were simultaneously tested for total protein, albumin, glucose, lactate dehydrogenase, adenosine deaminase, and amylase. RESULTS: The coefficient of determination (R2) for all six clinical chemistry test results between EDTA anticoagulated and anticoagulant-free body fluids are more than 0.95 with the exception of glucose in bronchoalveolar lavage fluid (R2= 0.78). CONCLUSIONS: EDTA anticoagulated specimen could be used for testing routinely requested clinical chemistry tests in body fluid analysis, that only one tube of specimen is necessary to perform cell count, differential count, and clinical chemistry tests.

The Value of Serum Procalcitonin Level for Differentiation between Contaminants and Pathogens in Bacteremia / 대한임상미생물학회지

BACKGROUND: Bacteremia is a life-threatening infection, and prognosis is highly dependent on early recognition and treatment with appropriate antimicrobial agents. We investigated the diagnostic performance of serum procalcitonin (PCT) for differentiation between contaminants and true pathogens in blood cultures. METHODS: Serum PCT, C-reactive protein (CRP) and blood culture were performed for 473 patients between February 2008 and October 2008. We retrospectively reviewed the patients' clinical characteristics and laboratory results based on medical records. RESULTS: The mean concentration of PCT was significantly different between the two negative and positive blood culture groups (6.45 ng/mL vs 28.77 ng/mL, P<0.001). Procalcitonin levels were found to be markedly higher in those with Gram-negative bacilli (mean+/-SD; 59.58+/-67.00 ng/mL) bacteremia than in those with Gram-positive cocci (mean+/-SD; 17.75+/-42.88 ng/mL) bacteremia (P<0.001). The areas under the receiver operating characteristic curves (95% confidence interval) for PCT and CRP were 0.880 (0.820~0.940) and 0.637 (0.538~0.736), respectively. The use of a PCT level of 2 ng/mL as a cutoff value yielded an 83.6% positive predictive value and a 77.4% negative predictive value for the detection of bacteremia pathogens. CONCLUSION: Serum PCT is a helpful diagnostic marker for rapidly and accurately distinguishing between contaminants and pathogens in blood cultures.

Evaluation of VITROS(R) 5,1 FS Automated Chemistry Analyzer / 임상검사와정도관리

BACKGROUND: VITROS(R) 5,1 FS (Ortho-Clinical Diagnostics, NY, USA) is a newly developed, fully automated analyzer that uses the dry slide type technology to process routine chemistry items, electrolytes, therapeutic drug monitoring and immunity items. We evaluated the usefulness of the VITROS(R) 5,1 FS in the aspect of precision, linearity, recovery rates and comparison. METHODS: We evaluated the analytical performance of the VITROS(R) 5,1 FS for sodium, potassium, chloride, total CO2, BUN, creatinine, glucose, amylase, total protein, albumin, ALT, AST, ALP, GGT, total bilirubin, unconjugated bilirubin, calcium and phosphorus. Commercialized quality control material, Performance Verifiers (Ortho-Clinical Diagnostics, NY, USA), chemTRAK(R).H (Medical Analysis Systems, California, USA) and patient' sera for evaluation of precision, linearity, recovery rates and comparison were used. MODULAR Systems (Roche Diagnostics, Switzerland) and CX3 (Beckman Coulter, California, USA) were used as a comparative analyzer to evaluate comparison study. RESULTS: Within-run and within-day coefficients of variation (CVs) of all items were below 5%. Between-day and total CVs were less than 5% in almost all items except of total CO2, amylase, ALT, AST, total bilirubin, unconjugated bilirubin and phosphorus. The linearities were statistically acceptable (R2>0.99) for all items (P<0.001). The recovery rates for all items were in the range of 96.20 to 111.45%. The comparison study indicated good correlation between VITROS(R) 5,1 FS and MODULAR Systems or CX3, and correlation coefficients of all items were above 0.975 except sodium (0.971) (P<0.01). CONCLUSIONS: VITROS(R) 5,1 FS showed satisfactory precision, linearity, recovery rates and comparison. Because it has features of one system with many capabilities, we recommend that VITROS(R) 5,1 FS would be used for the emergency laboratories in general hospitals with many examinations or in medium-sized laboratories with relatively small numbers of cases.