Where the Point is Care

i-STAT System Creatinine

Procedure Type:  Waived Testing:

Category: Patient Assessment

St. Peter’s Hospital Laboratory, 2475 Broadway, Helena, Montana 59601
Equipment and Materials Alternative Procedure
Specimen Electronic Simulator
Procedure QC
Special Considerations Safety Precaution
Performance Evaluation Maintenance

PRINCIPLE OF MEASUREMENT:

Creatinine is measured amperometrically. Creatinine is hydrolyzed to creatine in a reaction catalyzed by the enzyme creatinine amidohydrolase. Creatine is then hydrolyzed to sarcosine in a reaction catalyzed by the enzyme creatine amidinohydrolase. The oxidation of sarcosine, catalyzed by the enzyme sarcosine oxidase, produces hydrogen peroxide (H2O2). The liberated hydrogen peroxide is oxidized at the platinum electrode to produce a current which is proportional to the sample creatinine concentration.

See below for information on factors affecting results. Certain substances, such as drugs, may affect analyte levels in vivo.

If results appear inconsistent with the clinical assessment, the patient sample should be retested usinganother cartridge.

INTENDED USE:

The test for creatinine, as part of the i-STAT System, is intended for use in the in vitro quantification of creatinine in arterial, venous whole blood.

EQUIPMENT AND MATERIALS:

  1. ANALYZER: Analyzer is the i-STAT Portable Clinical Analyzer. When a sample-filled i-STAT cartridge is inserted into an analyzer for analysis, the analyzer automatically controls all functions of the testing cycle including fluid movement within the cartridge, calibration and continuous quality monitoring.
  2. CARTRIDGES are sealed in individual pouches or portion packs. Store the main supply of cartridges at a temperature between 2 to 8°C (35 to 46°F). Do not allow cartridges to freeze. Cartridges may be stored at room temperature (18 to 30°C or 64 to 86°F) for 14 days. Cartridges should not be returned to the refrigerator once they have been at room temperature, and should not be exposed to temperatures above 30°C (86°F). If the pouch has been punctured, the cartridge should not be used. Write the date on the cartridge box or individual cartridge pouches to indicate the two-week room temperature expiration date. Cartridges should remain in pouches until time of use. Do not use after the labeled expiration date. An individual cartridge may be used after standing 5 minutes, in its pouch, at room temperature. An entire box should stand at room temperature for one hour before cartridges are used.  Cartridge analysis time for Creatinine is typically 130 to 200 seconds.
  3. CONTROLS: i-STAT Controls for creatinine. i-STAT Level 1 Store at 2 to 8°C (35° to 46°F). Controls may be stored at room temperature (18 to 30°C or 64 to 86°F) for five days. Do not use after expiration date on the box and ampules. i-STAT System controls and calibration verification materials are validated for use only with the i-STAT System and assigned values may not be commutable with other methods. Further information regarding metrological traceability is available from Abbott Point of Care Inc.
  4.  ELECTRONIC SIMULATOR: The i-STAT System uses an internal Electronic Simulator every eight hour. The external simulator test is performed daily.
  5. BLOOD COLLECTION EQUIPMENT: Venipuncture: Plain plastic syringe without anticoagulant, or collection device with lithium, sodium, or balanced heparin anticoagulant.

Creatinine cartridges:

  1. Each i-STAT cartridge contains one reference electrode (when potentiometric sensors are included in the cartridge configuration), sensors for the measurement of specific analytes, and a buffered aqueous calibrant solution that contains known concentrations of analytes and preservatives. For cartridges that contain a sensor for the measurement of creatinine, a list of reactive ingredients is indicated below:
  3. Metrological Traceability:  The i-STAT System test for creatinine measures creatinine amount-of-substance concentration in the plasma fraction of arterial, venous, or capillary whole blood (dimension μmol L-1) for in vitro diagnostic use. Creatinine values assigned to i-STAT’s controls and calibration verification materials are traceable to the U.S. National Institute of Standards and Technology (NIST) standard reference material SRM967

SPECIMEN: Suitable Blood Specimen for Creatinine

  1. Fresh whole blood without anticoagulant collected in a plastic syringe. 
  2. Whole blood with anticoagulant collected in a collection tube with lithium, sodium, or balanced heparin anticoagulant.

IMPLEMENTATION: Procedure for Creatinine Cartridge Testing : Venous Draw only.

USE ONLY VENOUS DRAW

  1.  Follow Universal Precautions; wear gloves.
  2. Use two identifier to identify patient, according to lab specimen collection procedure.
  3. Explain procedure to patient.  
  4. Enter your operator ID number. Repeat if required.
  5. Enter the patient ID number. Repeat if required.
  6. Remove cartridge from foil pouch and place the cartridge on a flat surface.
  7. Obtain fresh whole blood without anticoagulant collected in a plastic syringe, or whole blood with anticoagulant collected in a collection tube with lithium, sodium, or balanced heparin anticoagulant.
  8. Apply the blood against the bottom of the sample well. Once in contact with the sample well, the blood will be drawn into the cartridge.
  9. Apply sample until it reaches the fill mark indicated on the cartridge.
  10. Fold the sample closure over the sample well.
  11. Press the rounded end of the closure until it snaps into place.
  12. Insert the cartridge into the cartridge port until it snaps into place.
  13. Enter additional parameters on the Chart Page, if required. View result on the analyzer’s display screen.
  14. Remove the cartridge after “Cartridge Locked” or LCK message disappears. The analyzer is ready for the next test immediately.
  15. Place analyzer in the Downloader/Recharger. Do not move analyzer while the message “Communication in Progress” is displayed.

Note: Do ensure that the instrument remains on a flat vibration-free surface for testing.

SPECIAL CONSIDERATIONS: Notes and Precautions

1.      Avoid the following circumstances
a Drawing a specimen from an arm with an I.V.
b Stasis (tourniquet left on longer than one minute before venipuncture)
c Extra muscle activity (fist pumping)
d Hemolysis (alcohol left over puncture site, or a traumatic draw)
d Icing before filling cartridge
f Time delays before filling cartridge
g Do not use glass syringe or glass transferring devices. Use only plastic capillary tube, pipette, or syringe to transfer sample from a tube to a cartridge.
 2.      Criteria for specimen rejection:
a Evidence of clotting 
b Incorrect cartridge procedure.The cartridge is designed to fill and seal correctly. However, the conditions described below may occur, especially during the training period. If the condition is not detected by the operator, the analyzer will detect the condition, halt the test cycle and display a cause message followed by the action message: “USE ANOTHER CARTRIDGE.”
Condition
Operator Action
Analyzer Display

Sample beyond fill mark.

If the sample flows only slightly beyond the fill mark, the cartridge can still be used. If the sample is close to or enters the air segment chamber, use another cartridge.

SAMPLE POSITIONED BEYOND FILL MARK

Sample not up to fill mark.

If the sample well fills but the sample does not reach the fill mark, ensure that the air vent (small hole on the underside of the cartridge) is not blocked. Tilt the cartridge slightly so that gravity aids the flow. When the sample starts to flow into the chamber, return the cartridge to the horizontal position.If the sample is considerably short of fill mark, the analyzer will detect the condition and halt the test cycle.

SAMPLE POSITIONED SHORT OF FILL MARK

Sample well empty.

If the sample reaches the fill mark, but the sample well is left completely empty, there may be insufficient sample for the test.

INSUFFICIENT SAMPLE

Air bubbles in sample.

If air bubbles are trapped in the sample chamber, discard the

cartridge and fill another.

INSUFFICIENT SAMPLE

Sample well overfilled.

If the sample well is so full that sample is seen above the

sample well after the sample chamber is filled, do not wipe or

absorb the excess with a gauze or tissue but draw the excess back into the syringe or a capillary tube. If the sample spreads over the outside of the sample well, an airtight seal may not form when the cartridge is closed. In this case the analyzer may not be able to move or position the sample over the sensors.

UNABLE TO POSITION SAMPLE

Sample clotted.

If the sample clots in the sample well the analyzer will not be

able to move or position the sample over the sensors.

UNABLE TO POSITION SAMPLE

Cartridge contaminated.

If sample spills onto the cartridge or if the cartridge has collected debris, discard the cartridge. Inserting a contaminated cartridge into the analyzer will cause debris to build up on the pins that contact the cartridge pads which will cause a cartridge or analyzer Quality Check code.

CARTRIDGE ERROR or ANALYZER ERROR

Sample pushed beyond fill mark.

Avoid applying excess pressure on the closure directly over the sample well as doing so may push the sample beyond the fill mark.

SAMPLE POSITIONED BEYOND FILL MARK

Cartridge sealed before sample reaches fill mark.

Closing the cartridge before the sample chamber has filled will stop the flow of the sample to the fill mark.

SAMPLE POSITIONED SHORT OF FILL MARK

Cartridge not  sealed before inserted into analyzer.

Failure to close the cartridge before inserting it into the analyzer will prevent sample movement and can cause the sample to flow backward and out of the sample well.

UNABLE TO POSITION SAMPLE.

EQUIPMENT AND PERFORMANCE EVALUATION:

Electronic Simulator: The i-STAT System uses an internal Electronic Simulator every eight hour. The external simulator test is performed daily.

Action: If “PASS” is displayed on the analyzer screen (after using the external Electronic Simulator):

  1. Remove the Electronic Simulator after the LCK or Simulator Locked message disappears from the display screen.
  2. Transmit the result to the Central Data Station.
  3. Use the analyzer as required.
  4. Note: If the internal Electronic Simulator is used, the “PASS” message will not be displayed on the analyzer screen. The “PASS” record will appear in the analyzer’s stored results for transmission to the Central Data Station

Remedial Action:

  1. If “FAIL” is displayed on the analyzer screen:
    1. Repeat the procedure with the same Electronic Simulator. If "PASS" is displayed use the analyzer as required.
    2. If “FAIL” still is displayed notify the Point-of-Care-Testing Coordinator.
    3. Record the failure in the i-STAT QC Log along with the action taken.
  2. If “PASS” is displayed with the second Electronic Simulator, then use the analyzer as required.

Cartridge Storage Conditions Verification

  1. Verify that the cartridges stored in the refrigerator are all within the expiration date printed on the boxes.
  2. Deliver any expired cartridges to the Point-of-Care-Testing Coordinator.
  3. Verify that the refrigerator did not exceed the limits of 2 to 8°C (35 to 46°F).
  4. Cartridges may be stored at room temperature (18 to 30°C or 64 to 86°F) for 14 days. Write the date on the cartridge box or individual cartridge pouches to indicate the two-week room temperature expiration date. Upon removal from refrigeration, a box of  24 cartridges requires one hour equilibration at room temperature before use. Individual cartridges require five minutes equilibration. A cartridge should be used immediately after it is removed from the pouch.
  5. Verify that room temperature did not exceed  30°C  or 86°
  6. Cartridges stored at room temperature should not be returned to the refrigerator.
  7. Document in the Temperature Log.
    • Action: If the temperature of the cartridge storage refrigerator is within the range of 2 to 8°C (35 to 46°F) use cartridges as required.
    • Remedial Action: If the temperature is outside the range of 2 to 8°C (35 to 46°F), quarantine the cartridges in the storage refrigerator. Notify the Point-of-Care-Testing Coordinator immediately. DO NOT USE the cartridges from this refrigerator. Record the QC failure in the i-STAT QC Log along with the action taken. DO NOT USE the cartridges that have been stored at room temperature past 14 days.

REFERENCE RANGE: (NORMAL VALUES):

Test/Abbreviation Units Reportable Range Reference Range
Creatinine/Crea mg/dl 0.2 -20.0 0.6 -1.3
µmol/L 18-1768 53-115
*Reference range according to i-STAT procedure manual.

To convert a creatinine result from mg/dL to µmol/L, multiply the mg/dL value by 88.4.
The i-STAT reference ranges for whole blood listed above are similar to reference ranges derived from
serum or plasma measurements with standard laboratory methods.

CLINICAL SIGNIFICANCE:

Elevated levels of creatinine are mainly associated with abnormal renal function and occur whenever
there is a significant reduction in glomerular filtration rate or when urine elimination is obstructed. The
concentration of creatinine is a better indicator of renal function than urea or uric acid because it is not
affected by diet, exercise, or hormones.
The creatinine level has been used in combination with BUN to differentiate between prerenal and renal
causes of an elevated urea/BUN.

For creatinine results: 
Greater than 1.0 mg/dl for female
Greater than 1.3 mg/dl for male
Consult the radiologist before performing a scan per Diagnostic Imaging: Reflex Orders Policy #110-0036  
Creatinine ranges verified by St. Peter’s Hospital Laboratory       

FACTORS AFFECTING RESULTS: INTERFERENCE 

Acetaminophen Creatinine results will increase by approximately 0.25 mg/dL (22 µmol/L) per every1 mmol/L of acetaminophen.
Ascorbate 0.227 mmol/L ascorbate will cause a 0.7 mg/dL (62 µmol/L) increase in creatinine.
Bromide 100 mg/dL (12.5 mmol/L) bromide will increase creatinine by 0.8 mg/dL (71 µmol/L)from an initial creatinine concentration of 1.0 mg/dL (88 µmol/L).
CO2 For Crea values below 2 mg/dL:For PCO2 values above 40 mmHg, the values are increased by 6.9% for every 10 mmHgFor PCO2 values below 40 mmHg, the values are decreased by 6.9% for every 10mmHg[Cr]corrected = [Cr]istat X { 1 - ( 0.069 X [(PCO2 -40)/10]) }For Crea values above 2 mg/dL:For PCO2 values above 40, the values are decreased by 3.7% for every 10 mmHgFor PCO2 values below 40, the values are increased by 3.7% for every 10 mmHgCr]corrected = [Cr]istat X { 1 - ( 0.037 X [(40 - PCO2 )/10]) }
Creatine 5 mg/dL (382 µmol/L) creatine will cause a 0.20 mg/dL (18 µmol/L) increase in Creatinine. For clinical situations in which creatine may be elevated, see note (1) below.
N-acetylcysteine 16.6 mmol/L N-acetylcysteine will cause a 0.4 mg/dL (36 µmol/L) increase in creatinine.
Hydroxyurea (Droxia®, Hydrea®) Hydroxyurea may cause significant errors in the measurement of creatinine with the i-STAT System. Use an alternative method to measure creatinine when patients have been administered hydroxyurea. See note (2) below for typical uses of this drug and note (3) below for details of the interference.

Notes:

The normal range of creatine concentration in plasma is 0.17–0.70 mg/dL (13 – 53 µmol/L) in males and 0.35 – 0.93 mg/dL (27 – 71 µmol/ L) in females Creatine may be elevated in patients using creatine supplements, experiencing muscle trauma or other primary or secondary myopathies, taking statins for hyperlipidemia control, or in patients with hyperthyroidism or a rare genetic defect of the creatine transporter protein.

Hydroxyurea is a DNA synthesis inhibitor used in the treatment of various forms of cancer, sickle cell anemia, and HIV infection. This drug is used to treat malignancies including melanoma, metastatic ovarian cancer, and chronic myelogenous leukemia. It is also used in the treatment of polycythemia vera, thrombocytopenia, and psoriasis. At typical doses ranging from 500 mg to 2 g/day, concentrations of hydroxyurea in patients’ blood may be sustained at approximately 100 to 500 µmol/L. Higher concentrations may be observed soon after dosing or at higher therapeutic doses.

For every 100 µmol/L hydroxyurea in the whole blood sample, creatinine will be increased by approximately 1.85 mg/dL (164 µmol/L), up to a whole blood hydroxyurea concentration of at least 921 µmol/L (maximum concentration tested). The magnitude of the bias is independent of the creatinine level over a range of at least 1.0 mg/dL (88 µmol/L) to 12.4 mg/ dL (1096 µmol/L

Bicarbonate up to 40 mmol/L, bilirubin up to 20 mg/dL (342 µmol/L), calcium up to 5.0 mg/dL (1.25 mmol/L), dopamine up to 13 mg/dL (0.85 mmol/L), methyldopa up to 2.5 mg/dL (118.4 µmol/L), salicylate up to 77.5 mg/dL (4.34 mmol/L), sarcosine up to 1.0 mmol/L, and uric acid up to 20 mg/dL (1190 µmol/L) were tested and found not to interfere with creatinine results.

*It is possible that other interfering substance may be encountered. These results are representative and your results may differ somewhat due to test-to-test variation. The degree of interference at concentrations other than those listed might not be predictable.  

ALTERNATIVE PROCEDURE: Should the i-STAT System become inoperable for any reason, specimens should be collected and submitted to St. Peter’s Hospital laboratory for testing.

ELECTRONIC SIMULATOR:

Overview The Electronic Simulator, external and internal, is a quality control device for the analyzer’s cartridge signal-reading function. It simulates two levels of electrical signals that stress the analyzer’s cartridge signal detection function both below and above measurement ranges. While the analyzer performs internal electronic checks and calibration during each test cycle, the Electronic Simulator test provides an independent check on the ability of the analyzer to take accurate and sensitive measurements of voltage, current and resistance from the cartridge. An analyzer will pass or fail this electronic test depending on whether or not it measures these signals within limits specified in the analyzer software. The schedule for the Electronice Simulator can be customized to meet local, state, or national accreditation requirements. A reminder message for the operator to run the external simulator can be set by the number of hours on the i-STAT Portable Clinical Analyzer and by the hours or tests on the i-STAT 1 Analyzer. The schedule for the automatic internal Electronic Simulator can be set by the number of hours on the i-STAT Portable Clinical Analyzer and by the hours or tests on the i-STAT 1 Analyzer. For details and lockout options, see the Customization section of this manual.

Relative Humidity The Electronic Simulator test will fail if high humidity interferes with the measurements. Therefore it is not necessary to record humidity where the analyzers are in use.

Internal Simulator When the specified time has elapsed since the last Electronic Simulator test (internal or external), the internal test will automatically be performed when a cartridge is inserted before the sample is tested, adding about 20 seconds to the testing cycle.

External Simulator

The external Electronic Simulator is a stable electronic device, which is inserted into the cartridge port. The test cycle for the external Electronic Simulator is about 60 seconds. (The test cycle for the internal simulator is shorter because it shares the initial part of the test cycle with the cartridge.)

QUALITY CONTROL:

PROCEDURE FOR EXTERNAL ELECTRONIC SIMULATOR:

Procedure for External Electronic Simulator
1.      Press ON/OF
2.      Press menu
3.      Press Quality Test
4.      Select Simulator
5.      Scan Operator ID
6.      Scan Simulator ID
7.      Remove cover protecting the simulator
8.      Insert simulator wait for result to be displayed before removing simulator
9.      Record the result on the Electronic Simulator Log

PROCEDURE FOR LIQUID CONTROL:. Creatinine cartridges, analyze i-STAT Level 1 Controls.

Procedure for liquid control testing.
1. Prior to use, allow one vial each of the liquid control to stand at room temperature for a minimum of 30 minutes.
2. Access the i-STAT Cartridge Control option under Quality Tests in the Administration Menu. Enter the required information. The analyzer allows 15 minutes (or the customized timeout) to insert the cartridge after the last data entry.
3. Immediately before use, shake the ampule vigorously for 5 to 10 seconds to equilibrate the liquid and gas phases.
4. To shake, hold the ampule at the tip and bottom with forefinger and thumb to minimize increasing the temperature of the solution. If necessary, tap the tip of the ampule to send solution back into the bottom section of the ampule.
5 Protect fingers with gauze, tissue or glove, or use an ampule breaker to snap off the tip of the ampule at the neck.
6. Immediately transfer the solution from the ampule into a capillary tube or syringe, and then immediately transfer the solution into a cartridge.
7. Immediately seal the cartridge and insert it into an analyzer – it is
important not to expose the solution to room air since this will alter
the results. Note: Since aqueous based solutions such as controls
lack the buffering capabilities of whole blood, the transfer process
from ampule to cartridge must be more expedient than with a
patient sample.
8. Compare results to the package insert values. If results are within the expected ranges, use the cartridges as needed.
9. Place analyzer in the docking station and transmit results to the Central Data Station.

Control storage and temperature of use.

Refrigerated storage at 2 to 8 °C (35 to 46 °F) should be maintained until the printed expiration date on the box and ampule labels. Control solutions may also be stored at room temperature for up to 5 days (18 to 30 °C or 64 to 86 °F). Prolonged storage at temperatures greater than 30 °C (86 °F) may cause changes in the values of some analytes. Do not use beyond the expiration date on the box and ampule labels. Best Results For best results, ampules, cartridges and analyzer should be at the same temperature. A separate ampule must be used for each cartridge being tested. Do not use the solution left in a syringe, ampule or capillary tube for additional testing of cartridges.

Equilibrate the ampule for approximately 30 minutes at room (ambient) temperature.

QUALITY CONTROL FREQUENCY:

  1. Level 1 Liquid Control testing should be performed:
    1. Weekly.
    2. When a new lot of cartridges is put in use.
    3. If the integrity of the i-STAT meter or cartridges are in question.
  2. Internal Electronic Simulator: The i-STAT System uses an internal Electronic Simulator every 8 hour.
  3. The external simulator test is performed daily.

REFERENCE RANGE: (NORMAL VALUES):

Test /Abbreviation Units Reportable Range Reference Range*
Creatinine/Crea mg/dl 0.2 - 20.0 0.6 - 1.3
µmol/L 18 - 1768 53 - 115
Reference range means the range of test values expected from 95% of fasting individuals presumed to be healthy.
Reportable range means the range of test values throughout which the measurement system’s results have been shown to be valid. *Reference range according to i-STAT procedure manual.

SAFETY PRECAUTIONS:

Exercise universal safety precautions at all times when handling the analyzer, cartridges, and peripherals to prevent exposure to blood-born pathogens.

GENERAL MAINTENANCE:

If the analyzer is placed on a wet surface or if any liquid is spilled onto it, dry the analyzer immediately. If liquid enters the following compartments, the analyzer may be damaged:

  1. The electronics compartment
  2. The battery compartment
  3. The cartridge port
  4. The test strip port

Downloader cleaning: The Downloader may also be damaged by liquid contamination. Unplug the power supply from the outlet and dry the Downloader completely. Clean the display screen and the case using a gauze pad moistened with any of the following:

  1. A mild non-abrasive cleaner
  2. Detergent
  3. Soap and water
  4. Alcohol
  5. 10% bleach solution
  6. PDI Super Sani-Cloth (solution of IPA, n-Alkyl dimethyl ethylbenzyl- and benzyl- ammonium chloride)

Rinse the case using another gauze pad moistened with water and dry. Avoid getting excess fluids in the seam between the display screen and the case. (PDI and Sani-Cloth are registered trademarks of Sani-System™ Brand Products, the Health Care Division of Nice-Pak Products, Orangeburg, NY, USA.)
Caution
  1. Exercise universal safety precautions at all times when handling the analyzer, cartridges, and peripherals to prevent exposure to blood-born pathogens.
  2. If the analyzer is not to be used for an extended period of time, the batteries should be removed to prevent leakage.
  3. Decontaminate the analyzer or Downloader whenever a specimen is spilled onto it.

TROUBLE SHOOTING:

There are three conditions under which the i-STAT System will not display results:

  1. Results outside the System’s reportable ranges are flagged with a < or >, indicating that the result is below the lower limit or above the upper limit of the reportable range respectively.  (See the table of Reportable Ranges.)  The < > flag indicates that the results for this test were dependant on the result of a test flagged as either > or <. Action: Send specimen(s) to the laboratory for analysis, if necessary.
  2. Cartridge results which are not reportable based on internal QC rejection criteria are flagged with ***. Action:Analyze the specimen again using a fresh sample and another cartridge.  If the specimen integrity is not in question, the results that are not suppressed should be reported in the usual manner.  If the result is suppressed again, send specimen(s) to the laboratory for analysis in accordance with the Laboratory Procedure Manual.
  3. A Quality Check message will be reported instead of results if the analyzer detects a problem with the sample, calibrant solution, sensors, or mechanical or electrical functions of the analyzer during the test cycle. Action: Take the action displayed with the message that identifies the problem. Refer to the i-STAT or i-STAT 1 System Manual’s Trouble shooting section or the “Analyzer Coded Messages” Technical Bulletin if necessary. Call point-of-care coordinator at St. Peter’s Hospital (phone: 447-2965) or bring i-STAT to the lab.

DOCUMENTATION:

Transmitting results from the i-STAT 1 Analyzer to the Data Manager: When I-STAT is placed in the Downloader/Recharger the data is transmitted to the patient’s chart in the Meditech system.

 SPH SITES PERFORMING CREATININE i-STAT SYSTEM TESTING: 
  Diagnostic Imaging MRI/CT techs

REFERENCES:

  1. i-STAT manual Art: 714336-00D 1-25-05
  2. I-STAT manual Art: 714183-00M
  3. D. S. Young, Effects of Drugs on Clinical Laboratory Tests, 3rd ed. (Washington, DC: AmericanAssociation of Clinical Chemistry, 1990).
  4. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics 4th Edition, CA Burtis, ER Ashwood, DE Bruns, ed., Elsevier Saunders Inc., 2006, page 2264.
  5. CLSI. Method Comparison and Bias Estimation Using Patient Samples; Approved Guideline. CLSI document EP9-A [ISBN 1-56238-283-7]. CLSI, 940 West Valley Road, Suite 1400, Wayne,Pennsylvania 19087-1898, USA 1995.
  6. P.J. Cornbleet and N. Gochman, “Incorrect Least-Squares Regression Coefficients in Method Comparison Analysis,” Clinical Chemistry 25:3, 432 (1979).
  7. CLSI. Interference Testing in Clinical Chemistry; Proposed Guideline. CLSI document EP7-P (ISBN 1-56238-020-6). CLSI, 940 West Valley Road, Suite 1400, Wayne, Pennsylvania 19087, 1986.
  8. Tietz Textbook of Clinical Chemistry
PLACED INTO SERVICE:  3-15-09

Policy Review:

SIGNED_________  SIGNED_________  SIGNED_________  SIGNED_________  SIGNED_________

DATE___________  DATE___________  DATE___________  DATE___________  DATE___________