Dimension Vista® System HIL FAQ Job Aid

Dimension Vista® system Sample Quality Assessment for Hemolysis (H), Icterus (I), Lipemia (L) Frequently Asked Questions SIEMENS www.siemens.com/diagnostics SIEMENS CONTENTS 1.0 HIL Background Information ........................................................................ 4 1.1 Where can I fi nd information about HIL confi guration, ordering, processing, alert indices and reporting? .............................................................................................4 1.2 Are HIL alert index values available for all methods? ..............................................4 1.3 What is an HIL Alert Index? .....................................................................................4 1.4 What type of samples can be used for HIL? ...........................................................4 1.5 Can HIL be used as a quantitative measure of hemoglobin, bilirubin and triglyceride? .............................................................................................................4 1.6 How is HIL scheduled and processed in the testing series on a sample?...............4 1.7 What are the various ways of requesting an HIL “test”? ..........................................5 1.8 What is the DBASTM code for HIL? ........................................................................5 1.9 How is the hemoglobin interference handled for DBIL? ..........................................6 2.0 Troubleshooting ............................................................................................ 6 2.1 What errors are generated for HIL? ........................................................................6 2.2 What other factors can affect the accuracy of the HIL indices? ..............................6 3.0 HIL Operational Questions ........................................................................... 6 3.1 What should I do when a result is accompanied by the “HIL interference” test report message? .....................................................................................................6 3.2 Why might I obtain an “HIL interference” test report message for a result that appears to be accurate? ..........................................................................................7 3.3 Why might I obtain an elevated H index on a sample that is icteric, but visibly hemolyzed? ..................................................................................................7 D-01499 • 06/11/2009 • Version 3.0 Siemens Healthcare Diagnostics, Inc. Page 2 SIEMENS 3.4 Why might I obtain an elevated H and/or I index on a sample that is not visibly hemolyzed or icteric? ..............................................................................................8 3.5 Why might I obtain an elevated L index value on a sample that is not visibly lipemic? ...................................................................................................................8 3.6 Why might I not obtain an elevated L index value on a sample that is visibly lipemic? ...................................................................................................................9 3.7 I ran HIL on two lipemic samples and obtained a higher L index on the sample that appeared to be less lipemic. Why might this be? ............................................9 3.8 I ran HIL and TRIG on two samples and obtained a higher triglyceride concentration on the sample that gave a lower L index. Why might this be? .........9 3.9 Is it appropriate to dilute a sample to eliminate HIL interference? ..........................9 3.10 What guidelines can be followed for handling lipemic samples to minimize lipemia interference? ..............................................................................................9 3.11 Why is there no H index confi gured for direct bilirubin? ........................................10 3.12 Should there be an H index confi gured for K, LDH, LDI and MG? .......................10 D-01499 • 06/11/2009 • Version 3.0 Siemens Healthcare Diagnostics, Inc. Page 3 SIEMENS 1.0 HIL Background Information 1.1 Where can I fi nd information about HIL confi guration, ordering, processing, alert indices and reporting? The HIL Technical Bulletin and the Dimension Vista® Operator’s Guide provide detailed information on the HIL features on the Dimension Vista® System. 1.2 Are HIL alert index values available for all methods? All methods on the Dimension Vista® were evaluated for HIL interferences. HIL Alert Indices are defi ned only for methods that are affected by HIL. There is no need for confi guring HIL alert indices for any method that is not affected by HIL. 1.3 What is an HIL Alert Index? The HIL Alert Index represents the level (concentration) of hemoglobin, bilirubin (unconjugated) and lipemia (Intralipid®) that produces an increase or decrease in the analyte concentration by greater than 10%. If the HIL index of a sample is equal or greater than the HIL alert index defi ned for a method, an HIL interference comment will be annotated with the analyte result. The HIL alert index is also referred to as a threshold level. 1.4 What type of samples can be used for HIL? Only serum and plasma are evaluated for HIL. HIL is not intended to be processed with whole blood, urine, CSF, calibrators, QC and survey samples. 1.5 Can HIL be used as a quantitative measure of hemoglobin, bilirubin and triglyceride? No. HIL is designed as an indicator of sample quality. The HIL Index represents an estimate of the hemoglobin, bilirubin and lipemia concentrations that were used in the assessment of HIL interferences for each analyte. Additionally, Intralipid® was used to assess lipemia interference and may not accurately correlate with the triglycerides in the sample due to differences in turbidity and light scattering properties of various types and sizes of chylomicrons and VLDLs. Do not use results of interference testing to correct analyte results. Intralipid® is a registered trademark of Fresenius Kabi AG, Bad Homburg, Germany 1.6 How is HIL scheduled and processed in the testing series on a sample? On a Dimension Vista® 1500, HIL tests may use sample probes 1, 2 or 3 or the IMT probe for sample delivery to the cuvette. The probe to be used is determined at the time that the test is scheduled so as to maximize use of the instrument’s resources and to maintain throughput. D-01499 • 06/11/2009 • Version 3.0 The sample probe or the IMT probe delivers 10 μL of sample fl uid with 15 μL of chase (system water) to a cuvette containing 150 μL of system water. Siemens Healthcare Diagnostics, Inc. Page 4 SIEMENS On a Dimension Vista® 500, scheduling of HIL tests has no effect on throughput. The IMT probe delivers the sample to an odd-numbered cuvette, which is not routinely used on a Dimension Vista® 500. An HIL test is completed in approximately 1.25 minutes. Only one HIL test order is accepted per sample request. More than one HIL cannot be • requested on a single sample on the Manual Order Entry screen. Additional HIL requests from the LIS are ignored. In the “if needed and always mode”, the HIL request is not added if there is a manually ordered HIL request. HIL will NOT be automatically added to orders for samples prediluted by the user as • indicated by entry of a dilution factor. The user cannot add HIL requests to a sample that has been manually prediluted. If the LIS orders an HIL test on a sample that was manually prediluted, the HIL request is ignored. HIL tests are automatically added to surplus samples. Surplus samples are samples that • are loaded onto the instrument in a surplus rack. • HIL cannot be added to a panel. The user can delete a manually ordered HIL test. However, if an HIL test will be • automatically ordered by the system, the HIL test cannot be deleted. To avoid HIL being ordered automatically, load the sample on a sample rack confi gured for limited samples. 1.7 What are the various ways of requesting an HIL “test”? HIL can be ordered as a discrete “test” from either the LIS or User Interface as with any • other method. HIL may be automatically scheduled as part of a ‘refl ex test’, i.e., if a result triggers an • analyte that requires HIL and an HIL has not already been processed on that patient sample, it will be scheduled (with the exception of limited racks). HIL can be ordered automatically for an Open Channel, a Flexible Channel, or a JFlex • method if applicable. If additional analytes are ordered via the ‘Edit Sample’ or ‘Refl ex Featuring’ function, and • HIL is in the ‘Auto On’ mode, the system will re-assess whether to order an HIL. If analytes are deleted via the ‘Edit Sample’ function, the system will not delete any HIL that • may have been ordered. If the ‘Rerun Sample’ function is selected, the system will not automatically recall the result • of any previous HIL result. The system will create a new feature-list with or without HIL as it would for a newly-entered sample. This is true for surplus samples only. 1.8 What is the DBASTM code for HIL? LIS orders the HIL test with the code 0835. D-01499 • 06/11/2009 • Version 3.0 Siemens Healthcare Diagnostics, Inc. Page 5 SIEMENS 1.9 How is the hemoglobin interference handled for DBIL? In the Auto On mode the hemoglobin index generated on a sample is linked with the direct bilirubin result. The result for direct bilirubin on a sample containing a hemoglobin concentration above 50 mg/dL (H index of 3-8), will be annotated with a Hemoglobin interference comment. 2.0Troubleshooting 2.1 What errors are generated for HIL? Process errors: If a process error occurs while processing an HIL request, the HIL request is retried. If it encounters a second error, the HIL request will report the process error. No H, I, or L interference comments will be produced for the other tests with potential interferences. If the user wants the HIL comments, the entire sample must be rerun. 2.2 What other factors can affect the accuracy of the HIL indices? Preanalytical: Specifi c samples such as those obtained from patients with multiple myeloma may cause erroneous absorbance readings due to precipitation of atypical proteins. HIL indices generated from these samples may not be accurate. Listed below is a table describing problems and potential corrective actions. Problem Corrective Action Insuffi cient or no sample Confi rm for suffi cient sample. Grossly lipemic sample Ultracentrifuge or clarify and rerun sample. Fibrin in sample Remove fi brin or replace with fi brin free sample. Diluted sample HIL must use undiluted serum and plasma only. Incorrect sample type (e.g. urine or CSF) HIL must use serum and plasma only. Sample or Reagent probe problem Replace Sample and Reagent probes; realign. Sample probe tubing crimped or leaking Replace sample probe tubing. IMT tubing crimped or leaking Check IMT tubing for air leaks. 3.0 HIL Operational Questions 3.1 What should I do when a result is accompanied by the “HIL interference” test report message? Visually inspect the sample. Follow your laboratory’s procedure for reporting results when the sample is hemolyzed, icteric, and/or lipemic. D-01499 • 06/11/2009 • Version 3.0 Siemens Healthcare Diagnostics, Inc. Page 6 SIEMENS 3.2 Why might I obtain an “HIL interference” test report message for a result that appears to be accurate? HIL index value(s) exceeded the alert Index values(s) entered for that method. • The analyte concentration is signifi cantly different (typically higher) than the concentration at • which interference testing was performed. The concentration of the analyte in the sample is at the low end of the reference interval. • HIL testing was performed at H, I, L concentrations at the high end of the index range. 3.3 Why might I obtain an elevated H index on a sample that is icteric, but visibly hemolyzed? The H index is measured at 405 nm and the I index is measured at 452 nm. Signifi cant absorbance from a highly icteric sample may carryover to the 405nm, the wavelength at which hemolysis is measured. Bilirubin (Unconjugated) Absorbance Spectrum 1600 1400 1200 1000 800 600 400 200 Air-Blanked Result (mAU) 0 .200 300 350 400 450 500 550 600 650 700 Wavelength (nm) D-01499 • 06/11/2009 • Version 3.0 Siemens Healthcare Diagnostics, Inc. Page 7 SIEMENS 3.4 Why might I obtain an elevated H and/or I index on a sample that is not visibly hemolyzed or icteric? Signifi cant absorbance from a highly lipemic sample is detected at 405 and/or 452 nm, the wavelengths at which hemolysis and icterus are measured. Additionally, it is possible that another unknown interferent may be present in the sample. Intralipid (20%) Absorbance Spectrum 1600- 1400 1200 1000 800 600 400 200 Air-Blanked Result (mAU) 0 -200 300 350 400 450 500 550 600 650 700 Wavelength (nm) 3.5 Why might I obtain an elevated L index value on a sample that is not visibly lipemic? The HIL feature detects light scattering at 700 nm generally due to the presence of large particle lipoproteins (i.e., chylomicrons and VLDL). Visual lipemia will vary based on the size and distribution of lipoproteins on individual patient samples. Patients receiving some chemotherapy drugs or activated charcoal may produce a false lipemia error. Samples with circulating immunocomplexes such as rheumatoid factor may generate false lipemia errors. Refer to the Dimension Vista® HIL Technical Bulletin for additional information on Limitations of Lipemia Interference. D-01499 • 06/11/2009 • Version 3.0 Siemens Healthcare Diagnostics, Inc. Page 8 SIEMENS 3.6 Why might I not obtain an elevated L index value on a sample that is visibly lipemic? The HIL feature detects light scattering at 700 nm generally due to the presence of large lipoproteins (i.e., chylomicrons and VLDL). The sample may contain smaller particle lipoprotein (i.e., LDL and HDL) that are not likely to scatter light at 700 nm. Refer to the Dimension Vista® HIL Technical Bulletin for additional information on Limitations of Lipemia Interference. 3.7 I ran HIL on two lipemic samples and obtained a higher L index on the sample that appeared to be less lipemic. Why might this be? High levels of lipemia can variably decrease transmission due to light scattering and the heterogeneity of endogenous lipid species prevents measured triglycerides levels in the specimens from correlating with visual lipemia or the lipemia index (L). 3.8 I ran HIL and TRIG on two samples and obtained a higher triglyceride concentration on the sample that gave a lower L index. Why might this be? Due to heterogeneity of endogenous lipids, triglyceride concentrations do not correlate well with spectral measurement of lipemia. 3.9 Is it appropriate to dilute a sample to eliminate HIL interference? Hemolysis: Not recommended. Icterus: Not recommended. Lipemia: For optimal results, specimens should be cleared of visible lipemia before analysis. 3.10 What guidelines can be followed for handling lipemic samples to minimize lipemia interference? It is the responsibility of the laboratory to validate their chosen procedure. Ultracentrifugation or Use of a Lipemia Clearing Agent • High levels of lipemia in patient specimens can affect reported test results as well as hemolysis and icterus index values. For optimal results, specimens should be cleared of visible lipemia, before performing analysis. • Dilution The result from a diluted sample may not be accompanied by the “HIL interf” message, however, spectral interference may still impact the result after it has been multiplied by the dilution factor. D-01499 • 06/11/2009 • Version 3.0 Siemens Healthcare Diagnostics, Inc. Page 9 SIEMENS A single dilution is not recommended; several dilutions should be analyzed simultaneously to determine the best response.1 Multiple serial dilutions are required to verify convergence of values. 1 Reference: Kaplan LA et al., Third Edition Clinical Chemistry, 1996; 427-428 3.11 Why is there no H index confi gured for direct bilirubin? The software on the Dimension Vista® Sytem for bilirubin will automatically generate a “Hemolysis Interference” comment on a sample that contains 50 mg/dL or greater of hemoglobin. 3.12 Should there be an H index confi gured for K, LDH, LDI and MG? An alert H index of 3 equivalent to 25-50 mg/dL of hemoglobin is recommended for these analytes that have increased intracellular concentrations. D-01499 • 06/11/2009 • Version 3.0 Siemens Healthcare Diagnostics, Inc. Page 10