Program for Chemistry SOP

Department of Pathology
Core Laboratory
Chemistry QC Program SOP
Author: Department of Pathology.
Core Lab
Document Origin: Internal Procedure
Document Number:
Effective (or Post) Date:
09 Feb 2009
Johns Hopkins
SMILE Approved by:
Orlinda Maforo
Review by
Heidi Hanes
Review date
7 Feb 2012
SMILE Comments: This document is provided as an example only. It must be revised to
accurately reflect your lab’s specific processes and/or specific protocol requirements.
Users are directed to countercheck facts when considering their use in other applications.
If you have any questions contact SMILE.
CHA.1100 Version 1.3
Effective: _____________
Quality Control is required for all testing procedures performed in the clinical
laboratory to standardize operations for all automated and manual chemistry. Pre-analytic
and post-analytic standards follow the Laboratory Quality Management and Quality Control
Plan. Specific pre-analytic or post analytic requirements are documented in test
procedures as needed.
Clinical Significance:
A formal Quality Control Program is a summary of the overall effort of a laboratory to
review the analytical results of samples of known value, interspersed randomly among the
unknowns, as an indicator of a well functioning system. It is designed to conform to the
objectives of the Pathology Department Quality Management Program. A test that is “in
control” is assumed to be producing reliable results for use by health care providers in
diagnosing and treating patients.
Definitions for various statistical terms utilized in a Quality Control Program can be found in
the NCCLS guidelines for Laboratories.
Quality Control procedures in the clinical laboratory are based on a statistical
process including the performance characteristics of reagents utilized with the analyzer
system or kit. Control materials should exhibit behavior that is both reproducible and
quantifiable. Repeated measurements of a single substance will fall into a Gaussian
distribution that can be represented statistically.
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A. Materials
The material used for quality control is usually a commercially available preserved liquid
product or a lyophilized product. A quantity of a single lot of the product is obtained, in
single or multiple shipments, to allow the use of the same material over an extended
period. A general target is a year’s supply if it does not outdate.
The product may be assayed or non-assayed. Package insert ranges for assayed controls
may be used only until there is sufficient data to calculate the internal mean and standard
deviation for each analyte used. Non-assayed controls may not be placed into service
until the mean and standard deviation for each analyte has been determined
When troubleshooting, a control can also be other materials such as calibrators,
proficiency materials, previously reported patient samples, etc. However,
calibrators used for controls may not be the same material that was used for the
current calibration. Freshly diluted and/or opened materials or that of a different lot
must be utilized.
All solutions (Reagents, Control Materials and Calibrators) must be properly
1. Vendors usually supply content, quantity and concentration.
2. Storage requirements: vendor supplied but once opened or on board
an instrument, requirements that change must be added to the
3. Date prepared, opened or reconstituted must be on the container.
4. Expiration date: vendor supplied but once opened or on board an
instrument requirements may change and these must be added to the
B. Performance
The performance of the quality control material must be determined for each analyte it is
used for. This involves preparing several vials of controls for use over several days and
determining the concentrations of the desired analytes. Multiple technologists and shifts
should be involved to get a representative picture of the performance of the material of an
entire run.
Generally, at least ten (10) and preferably twenty (20) determinations are required. The
data generated is used to calculate the arithmatic mean (average result) and standard
deviation (variance from the mean). Some pocket calculators and some computer
programs can perform these calculations.
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Statistically, 68.2% of the results will be within  1 standard deviation from the mean,
95.5% will be within  2 standard deviations from the mean, and 99.7% will be within  3
standard deviations from the mean.
Multiple controls (2 or 3) with different mean values must be used. These may be low/high
levels or clinically normal/clinically abnormal levels. CLIA ’88 mandates the minimum level
of quality control to be, that which is recommended by the manufacturer of the analytical
The whole quality control system depends on stability. A number of factors will affect the
stability of the instrument/reagent analytical system. These include:
1. Environmental factors such as temperature and humidity
2. Quality of water used by the system, or for reconstitution of controls and
3. Recalibration of an existing lot of reagent
4. Change of reagent lot
5. Service to the analyzer
6. Deterioration of reagent or of control
7. Instrument mechanical wear or lamp problems
Any of the above may affect results of quality control specimens and patient samples and
could compromise patient care.
Some of the effects of these factors can be anticipated. A change in performance due to a
calibration or reagent lot change may be expected. Major service to an analyzer can also
be expected to change performance. In these cases, the analytical performance of a test
around the mean does not change; it is the mean that has changed. This is referred to as
a “shift”. In such cases the material must be re-assayed and a new mean assigned. A
minimum of 5 – 10 patient results before and after should be examined to ensure changes
in mean are not associated with changes in patient values.
The other factors will cause drift away from the mean. This is referred to as a “trend”.
Deterioration of the reagent, the control, or the analyzer may result in values that start
within the acceptable control range and progressively move further away from the mean,
eventually exiting the range. The sooner a trend can be recognized, the sooner it can be
In most situations trends are minor and not clinically significant. Attempts should be made
to determine the cause of a trend and institute corrective (remedial) action if it is indicated.
Quality Control must be performed, and the results must be acceptable, before any
patient result can be released.
Quality control ranges for each analyte will be stored in those analyzers that support
quality control data storage.
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All major laboratory instruments are interfaced to the Laboratory Information System (LIS).
Quality control data from these instruments is uploaded to LIS
Quality control data for instruments that are not interfaced is entered in LIS manually.
At this time the following analyzers support on-board quality control but are also filed in the
1. Bayer Centaurs
2. Bayer 1650 Analyzers
3. Bayer Blood Gas Instruments
4. Bayer Atlas Urinalysis Instrument
All controls for quantitative tests must be within  2 SD of the assigned mean. Any value
outside of these ranges must be investigated and resolved.
Suggestions are:
Rerun the control. Pour a fresh sample cup.
If another vial of the control is available use that. Otherwise prepare a
fresh vial.
3. No more than 2 control reruns (same vial, new vial) should be made. If
this does not solve the problem begin troubleshooting. Do Not report
patient results.
4. Check analyzer maintenance, reagent, calibrations or kit for problems.
Has the reagent outdated, or been open longer than manufacturer’s
recommendations? Has calibration been performed? Does it need to be
performed? Has maintenance been performed? All instances of control
problems must be documented along with the corrective (remedial)
Use of controls for kit forms of patient testing:
Controls are run on reagents or test kits each day of use or with each run depending upon
method, manufacturer instructions and compliance requirements. The manufacturer’s
instructions should be followed for the frequency of testing of external controls on test kits
that utilize Internal controls.
For external controls, at minimum, a positive and negative control should be run.
Reactive, weakly reactive, and nonreactive controls are used where results are reported in
this fashion. Semi-quantitative (titer) procedures include a positive control, run at two or
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more levels, and a negative control. Whenever possible, patient samples are included in
lot-to-lot testing.
Documentation of internal control must be included with the external controls. If the
internal control does not respond as expected, a re-run is to be performed from same box.
If second device fails internal control, the lot is to be removed from service; a new lot QC’d
and information left for the Section Manager and Materials Management.
Acceptable Control results for these types of reactions:
A “positive” control must be positive; a “negative” control must be negative.
Internal controls must react as described in the manufacturer’s instructions.
Semi-quantitative (titer) procedure control results should agree within ± 1 level.
Graded control results may be reported as +1, +2, etc or Small, Moderate, Large, or as
defined for the specific method by the manufacturer; and must come within the required
C. Review of Quality Control:
Weekly review:
The Supervisor or Designee reviews all quality control weekly. Various computer functions
are utilized to review QC. Comment is used to document an entry for various reasons on a
specific control, date and shift. Review Function #20 (Analysis Statistics) or #32 (Data
Review Report) is used for review of a specific analyte and level on screen following the
prompts or printed utilizing any accessible printer..
Special access to Control dictionary is needed to adjust the Mean; Standard Dev.; add
new control information, etc. Correction comment of incorrectly entered data such as
wrong level of control will be made upon review. All instances of out of range controls will
be followed up to be sure there is adequate commenting and, where necessary, corrective
action. All actions will be documented on weekly review log along with initial and date of
review. Tech ID is noted on the results and can be looked up using Data Review function
of QC or #31.
All control results are entered on a daily basis. Instrument QC is auto-entered into Active
file as defined in this function. File N is used to enter information on new lots being run for
points in conjunction with current lot. File A, is current lot in use. New lot is advanced to
current use after correlation studies performed for 10 to 20 days concurrent with lot in use.
Monthly review:
The Section Manager, Supervisor or delegate, must print Quality Control charts monthly.
The Section Manager is then responsible to review for shifts, trends and bias.
Documentation must be made on the charts after investigation of any of the above
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variances. Major shifts are to be called to the attention of the Section Manager or
Pathologist in charge of the section.
Statistics will be submitted monthly to Vendor for Interlaboratory comparison where
applicable. Internal review utilizing month-to-month statistical variation from computer
printouts will be used where no peer group is available. SDI’s of 1.0 are the goal, but are
acceptable to 1.5. Between 1.5 and 2.0 investigation and monitoring should occur. SDI >
2.0 requires immediate investigation.
CV's are established for each parameter and monitored monthly through peer group
analysis and/or internal month-to-month comparison. Reagent/Instrument vendor
statistical ranges may also be utilized. A shift of + 2% of the CV from the departmental
established limits requires investigation and documentation. (See Attached analyte
specific variance sheet – CHA.1908
Action Protocol for Imprecision changes:
When the CV rises above our designated imprecision cutoff level, investigation is
Examine the precision statistics to confirm the accuracy of the calculations, determine the
duration and onset of the increased imprecision and compare to other instruments where
Random errors are likely caused by lack of reproducibility in the pipetting of samples and
reagents to the dissolving of reagent tablets and mixing of sample and reagents. Alto the
lack of stability of temperature baths, timing regulation and photometric and other sensor
errors. Individual analytical methods may not be subject to all of these possible sources of
When the type of error cannot be easily identified and quantified from available control
data, a replication experiment is designed to estimate the contributions from several
different components. Duplicates may be analyzed within a run for several different runs.
The data is used to determine the components of within-run and between-run variation.
This may help identify the sources of random error. See NCCLS EP15-A, Fol.21, No.25,
5.1 on page 6 for protocol.
Contact manufacturer if unable to resolve.
There will be a monthly review performed by the Manager or other appropriate supervisory
staff followed by additional review by the Pathologist, Medical Director and/or Laboratory
Administrative Director when appropriate. QC failure requiring corrections to patient
results already released must be documented on the Occurrence Report Form and the
pathologist notified immediately.
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Daily review of QA report is performed by the Manager or designee for reporting of critical
value failures. This process allows review of spurious patient failures and any trends that
may be occurring.
Review of manual procedure from worksheet recording to data entry and final review on
patient result form is performed on a regular basis (daily when possible). Corrective
action, if any, is to include Occurrence Report Form and associated documentation.
1. Sign on to LIS and select the Laboratory Module
2. Select number 31 QUALITY CONTROL and either number 20 Analysis or #32
(Data Review Report) for review of a specific analyte and level on screen
following the prompts or printed utilizing any accessible printer. Follow
prompts and enter desired Control, Lot, Test, Method and pertinent
information. Use F9 (Lookup) at each step if necessary.
Number 32 can also be used to review more than one control, method or
analyte at the same time.
3. Graph type would be LJ/Point
4. System will display information based on entries in #2. To expand the
information for #20, you may select OPTIONS.
A. Magnify Date
E. Change Graph Style/Type or Effect
B. Magnify Range
F. Trend Analysis
C. Change Date Rang
G. Print Graph
D. Select Tech/Shift or
H. Select Sites
Selection of B will allow the view all all data points entered.
The laboratory will retain all quality control data and printouts for two years. Storage does
not need to be on-site.
D. Proficiency Testing:
Proficiency Testing is an integral part of Quality Control. Surveys will be performed for
every test performed in the clinical laboratory. This laboratory currently subscribes to the
College of American Pathologists Proficiency Testing Program. Other vendors may be
added to meet changing needs. Samples will be identified as Survey specimens and will
be integrated into the normal workflow with routine patient specimens.
Although there are no current tests performed without PT available there can be one
instituted at any time. For those tests that do not have a survey available, alternate PT
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methods will be used. This can include split samples sent to a reference lab, split samples
among techs or comparison of manual method with analyzer method Proficiency testing
will be done at least two times a year per analyte. For in-house proficiency testing, the
results will be documented on the Alternate Proficiency Testing form; all supporting
documents attached and then submitted to the Manager for review. See ADM.0530,
section D.
Survey samples may not be sent to a reference laboratory or another hospital laboratory.
Interlaboratory communication about proficiency testing samples prior to results
submission is prohibited.
Testing for each analyte will be done on the instrument routinely used for that analyte.
On automated instruments, results will be taken from the report generated from the
Laboratory Information System through the instrument interface. The first valid result
obtained will be entered on the PT result form. Tests will not be run in duplicate, triplicate,
etc, unless this is routinely done for patient specimens.
If the first result is beyond technical limits, an appropriate dilution will be prepared and the
test repeated until a valid result is obtained. Only approved dilution protocols for the
individual analyte will be used.
If unusual results are obtained, which would normally prompt a request for review by a
second technologist or supervisor, or consultation from a Pathologist, it is appropriate to do
There will be no discussion of any survey with colleagues in other laboratories or re-runs of
material on alternate instruments, before results are submitted to the accredit ting agency.
Results will be recorded on the PT result input form according to the PT Agency's
instructions. Since this is not a form routinely used for patient reports, it is appropriate for
a second technologist or supervisor to review the results for clerical error before
submitting. Testing personnel must sign the attestation statement
Results will be transmitted to the PT Agency by mail, FAX, on-line data entry or as
otherwise specified in the instructions. The QA coordinator will be notified of completion.
Once results are entered for the analytes on the Proficiency Samples, the samples may be
run on alternate instrument for correlated comparison upon receipt of Proficiency report.
Results from all methods and instruments are recorded and compared with results
received later from the PT agency. Such testing is necessary to insure that results from
different instruments and methods are comparable.
Survey evaluations are received an average of six weeks after submission. The
Laboratory Administrative Director and then the Laboratory Department Manager or other
designee reviews the evaluations. Problems, if any, will be researched and a discrepancy
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report completed. The cause of the discrepancy will be determined and if possible
corrective action will be indicated. Pathologist will then review the evaluation. The
Medical Director and Administrative Director will respond to the CAP and Maryland State
Department of Health and Mental Hygiene as required for any deficiencies.
Survey evaluations and worksheets will be retained for two years. Storage need not be
E. Calculation of ranges:
Controls are available in two primary categories, assayed and unassayed. Ranges for
both categories must be developed in-house. Package insert ranges for assayed controls
may be used only for those procedures performed very infrequently. Developing in-house
ranges is not practical in this circumstance.
Use the package inserts to verify what constituents are present. Do not attempt
to develop a range for an analyte that is not listed.
Over the course of several days analyze the control for each desired analyte.
This should encompass several vials of control, multiple technologists, and all
shifts. Run in duplicate each time until a minimum of ten (10); preferably twenty
(20) values have been obtained. Retain all printouts.
Using the data supplied by the vendor as a guideline, review the data obtained in
the laboratory to calculate the mean and  1 standard deviation (SD). Also
calculate the coefficient of variation (CV). Examine the data.
Use the derived mean and SD to calculate 2 and 3 SDs and ranges for all the
parameters. Verify all calculations. Enter the appropriate numbers into each of
the analyzers that support QC. Post the means and ranges for analyzers not
supporting QC. Enter the appropriate numbers into LIS.
Monitor performance. Minor adjustments are sometimes needed.
Control Rules:
Controls should be run with initial patient run of the shift. The technologist must assure
that the displayed results upon data entry are within ± 2 SD of the assigned mean
Two Controls:
both are within  2 SD.
one within  2 SD/one is between
2-3 SD, (R12S)
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consecutive runs, the second run is
not acceptable (R22S)
one control is greater than  3 SD
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Three controls:
three are within  2 SD.
two are within  2 SD/one is
between 2-3 SD
one control is between 2-3 SD for two
consecutive runs, the second run is not
acceptable (R2S3)
one control is greater than  3 SD
two or more results ± 2 - 3 SD
a) Set up another run using new controls and three patients from original run. If on re-run
the controls are in and patients still read their original results, all patients are okay to
release. Discard old controls.
Make sure the unacceptable control value is entered along with suitable modifier. If further
action is taken, be sure to enter appropriate documentation. Entry of a failure value
displays the failure rule and a graph. At MOD: prompt, enter appropriate code and
description of action; problem; resolution. In this way, the reason for a shift is documented
for the person reviewing the LJ charts.
b) If both old and new controls are out, hold all patient results. Check: temperatures;
Reagents and Calibration dates.
The following would indicate a shift is occurring; supervisory personnel must be notified.
Two consecutive results more than  2 SD from the mean on the same side.
All QC failures and variances must have corrective action documented.
G. Corrective Actions:
Corrective actions include, but are not limited to, the following. In all cases the Supervisor
should be consulted.
1. Set up another run using new controls and three patients from original run. If on
re-run the controls are in and patients still read their original results, all patients
are okay to release. Discard old controls. If controls still out, continue:
2. Check analyzer (or kit) for problems.
3. Is the control beyond the open vial expiration? If this is the case pour a fresh cup
or reconstitute a new vial as indicated. Run the new sample only once then
proceed to next level of troubleshooting.. Do Not continue to rerun controls
until an in-control result is obtained.
4. Has the reagent outdated, or been open longer than manufacturer’s
recommendations? Replace and rerun.
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5. Has the elapsed time of calibration exceeded manufacturer’s recommendations?
6. Has a lot or vial of reagent been changed, with or without calibration? Calibrate.
7. Has there been maintenance to the analyzer or other equipment? May need
calibration and/or reassignment of control mean.
8. Has there been a recent calibration? May need to recalibrate.
9. Has there been a power interruption to the instrument?
NOTE: All instances of control problems must be documented along with the corrective
(remedial) action. Documentation must be on a written log, via coded comments in LIS
and via comments in an analyzer’s QC module
No patient results are to be reported until the out-of-control situation has been
If investigation shows that there is (was) a systems problem and previous run is
questionable, the assigned technologist is responsible for:
Repeating all patient testing since the last acceptable Quality Control was run .
Use of alternate method to process all samples.
Call for service/request service of hotline.
Report to technical coordinator, designee or supervisor
H. Calibration Verification:
Calibrations should be verified immediately after calibration and at six-month intervals
where the calibration duration exceeds six months. This verifies that the calibration
settings have remained valid for a method. Methods that are recalibrated more frequently
than 6 mos. do not require a separate cal verification procedure. A shift greater than + 2
SD at change of Reagent Lot will also require CRR and AMR action.
At least three calibrators that span the reportable range should be run as “unknowns” after
calibration. The recovered values should be within 10% or 1 SD of the stated values. If
necessary a combination of two calibrators can provide an intermediate level. Controls
should be included with the run.
Calibration verification involving patient samples must assure that the same patients will be
used pre and post calibration. When duplicate instrumentation is utilized, the same
samples will be used on both analyzers.
A failure of this process will require investigation and recalibration before any
patient specimens can be analyzed.
I. Linearity:
AMR: The Analytical Measurement Range (AMR) is the range of analyte values that a
method can directly measure without any dilution, concentration, or other pretreatment not
part of the normal assay process.
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a. AMR validation is the process of confirming that the assay system will correctly
recover the concentration or activity of the analyte over the established AMR.
b. Materials used for validation must be known to have the matrix characteristics
appropriate for the method. In many cases the manufacturer will recommend
suitable materials.
c. Test specimens must have values that, at a minimum, are near the low, mid, and
high values of the AMR. Samples that are within 5% of the lowest limit and 10% of
the upper limit stated by the manufacturer will be utilized to verify the AMR.
Procedure for Verifying Linearity/Reportable Range:
Samples used may be previously reported high patient samples, alternate lot
of calibrators, controls or standards as recommended by the manufacturer or
appropriate to the system. At least three samples, and preferably more, that
bracket the reportable range should be used.
For patient samples, choose elevated pre-run patient and perform serial
dilutions with appropriate diluent to cover span of linearity.
Prepare an intermediate level for the high and low end by mixing equal
volumes of the “zero/diluent” and next lowest calibrator to prepare a standard
which is intermediate to those. The same procedure should be followed with
the high and next highest calibrators.
Calibrate the instrument
Run each sample a minimum of three times.
Calculate the following:
i. Mean of each run
ii. CV for each run ( target should be 5% or less for most levels)
iii. Range of acceptability (up to 50% in lower ranges and 5-10% in upper
Prepare a graph utilizing appropriate software program depicting the target
ranges on the X-axis and the mean obtained on the Y axis.
Manger to review all results with Pathologist.
Based on values obtained, changes to technical range will be made in all
Quality Control systems. (Instrument and LIS)
The linearity of the method/reagent/analyzer system must be verified prior to introduction
of a new method, when calibration verification fails to meet acceptable limits, after major
analyzer service, or at six-month intervals.
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Many analyzers use the low and high calibrators to establish cut-off limitsThis assures
readable results near the cutoffs.
The linearity is intended to validate the manufacturer’s reportable range for patient results.
It should not be used to extend that range. Patient results below the reportable range
should be reported as “less than” the lower limit. Those above the upper limit should be
diluted and rerun to get a result that may be reported, or reported as “greater than” the
upper limit. Not all methodologies are amenable to dilution. This will be detailed in the
method procedure.
B) CRR - Clinically reportable Range:
This is the range of analyte values that a method can report as a quantitative result,
allowing for dilution, concentration or other pretreatment used to extend the direct AMR.
For some instruments, the analytes are auto diluted when over-range and it is common
practice to dilute samples over range manually for those test systems that do not auto
Practice at Mercy Medical Center is to follow vendor definition of dilution ratios for all autodilute procedures and no further dilutions are made. However, if request is made by a
physician for further dilution, the pathologist may (at his discretion) allow further manual
serial dilutions.
Usually linearity studies will also cover the clinically significant range.
J. Correlation of Methods:
Correlation of results with another routine method, another instrument or a reference lab
may be used to estimate system error. A minimum of twenty specimens, which are
distributed through the reportable range, will be run in parallel and the resulting data
analyzed using a computer program such as Excel, Quattro Pro or Casco. A linear
regression will be performed on the data-pairs. The slope of a simple line, the correlation
coefficient, y-intercept and other parameters will be calculated. A regression line will be
calculated from the data. A graph showing the regression line and the data pairs will be
created. A slope of 0.97 – 1.03 and a correlation coefficient of 0.97 – 1.00 are desirable.
If there is a significant difference in methodology these values may not be attainable.
See Method Validation Procedure ADM.0510 for details.
All reagents much be checked prior to use. Parallel testing consists of running old
controls with new reagents and new controls with old reagents wherever possible. If
parallel testing cannot be performed, running controls and reagents against reference
materials is acceptable. See CHA.1904.
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If reagents are not used according to instrument and/or kit instructions, one of the following
1. Approval of the change sent by the manufacturer on letterhead and signed by a
company representative authorized to approve the change.
2. There must be validation data to support the modification and that reliable results
are consistent with original assay claims.
3. The Pathologist may approve a temporary variance. This must be documented on
a Variance Approval Form.
K. Interferences:
Interfering substances may pose a significant problem to the clinical laboratory, as results
do not represent the clinical conditions of patients. Information known to the manufacturer
at the time the procedure is released to customers is included in the procedure
documentation, including results of studies performed by the manufacturer and others.
L. Reference Intervals:
The Reference Interval (or Reference Range) represents the range of results that includes
most healthy persons. This information comes from manufacturers as part of their method
documentation and similar data widely published in textbooks. The ranges are
compared to the population of patients that use laboratory services. Reference ranges are
verified with the introduction of new test; change of method/or change in patient
The Pathologist may consult with other physicians about the appropriateness of ranges as
well. Physicians will be educated about changes by mail, memo, posters/flyers and/or
comments on reports. If physicians have any concerns about specific reference ranges
they may refer the concerns to the Laboratory Director or the Pathologist for investigation.
M. Carryover evaluations: manufacturer’s directions for the performance of carryover
studies should be utilized at all times.
Analyzer-Specific or Method-Specific Guidelines:
Note: All reconstitutions utilize Class-A volumetric pipettes or calibrated single-volume
mechanical pipets. Do not blow out the residual liquid from volumetric pipettes.
In all references to water (Distilled, Reagent Grade or Type) there is only one source
water system utilized here at Mercy Medical Center for dilutions. This system
produces Type I water. See Lab General for specific system.
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Controls: See attached appendix for each analyzer for current controls, their stability,
dilution instructions, etc.
Approved by:__________________________ Date:____________________
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