General Chemistry Scheme Guide

Transcription

1 General Chemistry Scheme Guide Copyright WEQAS. All rights reserved. No part of this document may be reproduced or utilised in any form without permission from WEQAS

2 Contents. Scheme details and repertoire..... Serum Chemistry.. Bilirubin.. Lipids.4. ED Tox Scheme. Instructions for use..4. Statistical Analysis.. Performance criteria Reference methods.. Comparability factors Filename: SP-QL-GENGUID6 Approved by: S.Jones Version. Date of Revision: //6 Page of

3 . Scheme details and repertoire The Scheme is accredited to ISO 74 for the following analytes. List of Analytes and Frequency of Distribution General Clinical Chemistry Scheme includes Serum Chemistry, Lipids, Bilirubin, and ED Tox Schemes.. Serum Chemistry Frequency : Monthly Number of samples : 4 Analyte Approx. Range Covered Sodium -6 mmol/l Potassium.8-7. mmol/l Chloride 8 - mmol/l Bicarbonate - mmol/l Urea. -. mmol/l Creatinine - 6 mol/l e-gfr < to 9 mls/min/.7m Glucose. -. mmol/l Calcium Adjusted Calcium mmol/l mmol/l Phosphate.4 -. mmol/l Total Protein 4-8 g/l Albumin - g/l Magnesium.4 -. mmol/l Urate -7 mol/l Lithium. -. mmol/l Osmolality -7 mmol/kg AST - IU/L IFCC ALT - IU/L IFCC ALP 8-4 IU/L SCE CK 8-8 IU/L SCE Gamma GT - 4 IU/L SCE Amylase - 6 IU/L LDH - IU/L SCE Iron - 6 mol/l TIBC Transferrin - - Transferrin saturation - 8 % mol/l g/l Gentamicin 4 - g/ml Lipase - IU/L Serum Indices Icteric, Lipaemic, Haemolysed and negative samples distributed. Filename: SP-QL-GENGUID6 Approved by: S.Jones Version. Date of Revision: //6 Page of

4 . Bilirubin Scheme Frequency : Monthly Number of samples : 4 Analyte Approx. Range Covered Total bilirubin - mol/l Conjugated bilirubin - mol/l. Lipid Scheme Frequency : Monthly Number of samples : 4 Analyte Approx. Range Covered Triglyceride.6 -. mmol/l Cholesterol mmol/l HDL cholesterol.6 -. mmol/l LDL cholesterol.. mmol/l Apolipoprotein A. -. g/l Apolipoprotein B. -. g/l Lipoprotein (a). -. g/l.4 ED Tox Scheme Frequency : Monthly Number of samples : 4 Analyte Approx. Range Covered Salicylate 8-8 mg/l Paracetamol 4 - mg/l Ethanol - 4 mg/l *Ethylene Glycol - mg/l *Methanol - mg/l *Whole Blood Ethanol - 4 mg/l *analyte not accredited Filename: SP-QL-GENGUID6 Approved by: S.Jones Version. Date of Revision: //6 Page 4 of

5 Instructions for use The base material is sterile human serum, filtered to. µm and gentamicin added to maintain sterility. The serum is dispensed and stored at - C. Stability experiments have been carried out to assess the decay of the analytes, and are available in a separate document. All human serum is tested at donor levels and found negative for HIV Ab, Hep B surface Ag and Hep C. Although every effort is made to ensure that the material is free from any known infectious agent, the samples should be handled as for clinical specimens. The samples are dispatched frozen, and will thaw in transit. Please ensure that the samples are well mixed before analysis. Please analyse on the day of arrival. If there is a delay in analysis please store at 4 C. Please note that most of the analytes in the General Scheme samples are stable for at least one week at 4 C. The least stable analytes are Creatine Kinase and Aspartate Transaminase. To minimise analytical bias due to denaturation of these enzymes, please store at 4 C and assay within days of receipt. The samples are stable for a month if frozen.. Statistical Analysis Please refer to the accompanying Participants Manual for full details on statistical analysis and interpretation of results.. Performance criteria Standard deviation limits used in the report are based on precision profiles calculated over several batches and are fixed for a given level of analyte. They are reviewed every two years and reflect the state of the art of the methods used. In the following graphs, each data point represents the standard deviation observed for each sample over a number of distributions and reflects the interlaboratory variation for that analyte. Different batches and timescales are illustrated on the graphs as different series. For the Serum samples, each series equates to a month period. The desirable quality specification derived from biological variation is also shown as yellow lines on all graphs except enzymes, iron, TIBC and transferrin. Sodium Potassium y =.4x -.8x +.76 R =.86 y =.6x -.4x +..4 R =.784 y =.9x -.46x R =.. y =.x -.87x + 8. R =.666 Batch - 6 Biological goal Batch -6 Series Series..... Batch -6 Biological goal Series Series Concentration (mmol/l) Filename: SP-QL-GENGUID6 Approved by: S.Jones Version. Date of Revision: //6 Page of

6 Chloride Bicarb y =.x +.86x +.94 R = y =.486x -.6x R =.7 y =.4x +.89x R =.876 y =.x -.x R =.4. y =.4x -.74x +.76 R =.69 Batch -6 Batch-4 Biological goal Series. Batch -6 Series Urea y =.479x R =.88 Creatinine y =.8x -.4x R = y =.x -.9x R = Batch -6.. y =.7x +.9x R =.969 Biological goals Series Poly. (Series) y =.x -.8x R =.97 Batch e GFR y =.x -.96x +.4 R = Glucose y =.9x +.848x R =.9899 y =.6x -.46x R = y = E-6x +.4x +.4 R =.778 Batch -6 Biological goals 6 Dist LA-LI Dist LJ-MT Series Overall Calcium Adjusted Calcium.6 y =.646x x R =.9 y =.77x -.4x R =.968 Batch y =.6x -.4x +. R = y =.6x -.7x +.7 Series.4 R = Overall Mean Filename: SP-QL-GENGUID6 Approved by: S.Jones Version. Date of Revision: //6 Page 6 of

7 . Phosphate y =.49x -.89x +.4 R =.84 Total Protein y =.8x -.84x +.6 R = y =.999e.99x..6 R = y =.x +.8x +.7 R =.676 Batch -6 Biological goals Series Batch -6 Series Albumin y =.77x -.x R = Magnesium y =.99x -.874x R =.868 y = -.x +.77x -.68 R =.99. y =.x -.68x +.6 R =.984 y =.x -.6x R =.766 Batch -6 Series y =.9x -.x +.44 Batch -6 Series R = Urate y =.68476x -.7x +.7 R =.89. Lithium y =.8x -.78x R =.848 y =.6x +.86x +. R =.68. Batch Series. y =.7x +.x +.9 R = y =.7e.4x R =.789 y = -.x +.x +.8 R = Batch Poly. (7-74) Expon. (79-8) 7 Osmolality y =.x -.6x R =.6887 ALT 6 y =.96x +.679x +.84 R =.9 y = E-x +.6x R =.7488 Batch " 7 Series Filename: SP-QL-GENGUID6 Approved by: S.Jones Version. Date of Revision: //6 Page 7 of

8 cv AST 8 CK y =.8x x +.7 R = y =.x +.46x R = y = E-x +.6x +.47 R = y =.9x R = GGT ALP y = -.9x +.76x R = y =.64x +.74x R = y = 9E-x +.6x +.9 R =.96 y = E-x +.6x +.68 R = Amylase y =.9x +.799x LDH y =.x +.468x R = Iron y =.4x -.697x +.69 R =.6887 TIBC y =.9x -.469x Feb '99 - March ' Feb ' - Oct ' Filename: SP-QL-GENGUID6 Approved by: S.Jones Version. Date of Revision: //6 Page 8 of

9 Transferrin PP y =.x -.7x +.9 Lipase R =.. 6. NW-OD current.x Dist 8- Dist MU-MZ biol goals. Poly. (79-8) y =.44x -.7x +.4 R =.47 Linear (biol goals) Transferrin overall y =.49x -.9x R =.896 Overall Mean (IU/L) ED Tox Scheme Paracetamol Salicylate y =.46x +.7x R = y =.87x.88 R = y = 7E-x -.96x R = Scipac Randox y =.466x R = Ethanol Precision Profile y =.6x +.49 R =.99 SP - SP6 4 4 Mean (mg/l) Filename: SP-QL-GENGUID6 Approved by: S.Jones Version. Date of Revision: //6 Page 9 of

10 trimmed overall Bilirubin Scheme 4 Total Bilirubin () batch - 4 batch Conjugated Bilirubin () y =.496x R =.8 batch - 4 batch y =.4x R =.9 y =.7x +.7 R = y =.66x +.9 R = Biologic goal TE = 6.9% - B7 - B Biologic goal, TE = 44.% - B-B8 - B9-B4 4 B9-B4 4 4 B - B4 B4 - B46 Linear (997-) y = -E-x +.4x +.4 R = Overall B-B4 B4 - B46 B-B46 Overall Linear (-) Lipid Scheme On the following graphs, the Total Error (desirable quality specification) from the European Biological Database is denoted as a yellow line. The used to calculate the I is also shown on the graph. Chol Trig precision.6. y =.4x..4 y =.4x.8..6 y =.6x. y =.x Chol (mmol/l) 8-9 Te= 8.% Te L6 - L = 6% - L76 L77 L L Te=% Te=8% L6 L77 L - L76 - L - L HDL precision profile Apo A precision..4. y =.8x.4. y =.4x -.8x +.87 R = y = -.x +.x -.49 R =.49. y =.4x.. TE= 9% y =.4x overall Te = 6% Te = 8% L - L Linear (Te = 6%) Te = 9% L6 - L76 L77 - L L - L Filename: SP-QL-GENGUID6 Approved by: S.Jones Version. Date of Revision: //6 Page of

11 . Apo B.9 LDL y =.98x +.86x R = CURRENT LINE. y = -.664x +.744x R = y =.x TE= %. TE.9% Te= % L6 - L76 L77 - L L - L L8 - L8 - L6 - batch 6 batch L9 L6 L76 L77 - L L - L TE =.9% Poly. (batch 7) Linear (TE =.9%) For Lipoprotein Lp(a), the current performance criteria is set at % for. Cholesterol performance influence of triglyceride concentration. The following data illustrates the precision profile for cholesterol over a year period. The first plot suggests that the interlaboratory variation (CV%) is not concentration dependent with a wide range of CVs at all concentrations. The second plot shows the same data taking into account the triglyceride concentration. The observed coefficient of variation (CV%) against cholesterol concentration (mmol/l) is plotted on the left primary axis and the corresponding triglyceride concentration (mmol/l) for each sample is plotted on the right secondary axis. A CV of <.% is observed for the majority of samples when the triglyceride is <. mmol/l, however above this value there is a marked increase in the interlaboratory variation for cholesterol. Filename: SP-QL-GENGUID6 Approved by: S.Jones Version. Date of Revision: //6 Page of

12 . Reference Methods The WEQAS reference laboratory is involved in the production of reference material and in the development and implementation of reference methods both for WEQAS value assignment and for commercial organisations. The WEQAS Reference Laboratory is part of a European Network of highly specialist laboratories providing accurate target value assignment of clinical material to assist in the global harmonisation of Pathology results. This is the only laboratory in the UK providing this service. The WEQAS Reference Laboratory uses primary and/or secondary reference methods in order to give stated, traceable, analyte values in calibrator, QC and EQA material. Where possible Certified Reference Materials (CRMs) will be used to corroborate target values. The WEQAS Reference Laboratory is accredited to ISO 7 and 9 for the following analytes: Flame Atomic Absorption/Emission Spectrometry Total Sodium Total Potassium Total Calcium Total Magnesium Total Lithium Gas Chromatography-Mass Spectrometry Creatinine Glucose Uric acid Cholesterol, Triglyceride UV-Vis Spectrophotometry Lactate Dehydrogenase, Gamma GT, AST and ALT All WEQAS Reference values are assigned by the WEQAS Reference Laboratory, except those detailed below. Cholesterol and HDL Cholesterol target values are assigned using the CDC Abel-Kendall reference method in an approved CDC network laboratory.. Comparability Factors For the enzymes, results are adjusted using known method comparability factors (CF), which include temperature correction factors to 7 C. Each specific method CF has been calculated from results received over an extended period using linear regression analysis of the data against the percentage enzyme added to the pool. These CF s will be dependent on the source and isoenzyme composition of the enzyme. Each laboratory's enzyme results can therefore be compared with their own method group and directly compared with the overall values of all groups. IFCC methods, where applicable, will be established by the WEQAS Reference Laboratory to give definitive values. Please contact WEQAS by telephone (9 7446) or (office@weqas.com) for a list of the current comparability factors. Filename: SP-QL-GENGUID6 Approved by: S.Jones Version. Date of Revision: //6 Page of

13 Copyright WEQAS. All rights reserved. No part of this document may be reproduced or utilised in any form without permission from WEQAS