1. QUALITY ASSURANCE IN THE CLINICAL CHEMISTRY LABORATORY

2. Introduction
There are many steps in the process between the clinician requesting a clinical biochemistry test and receiving a result.
Each of these steps must be subject to quality assurance techniques.
Clinical chemistry laboratories now have mature, integrated systems of internal quality control, external quality assessment and quality assurance to ensure that the results issued do aid in the provision of optimum patient care.
The recent initiation of a professionally led laboratory accreditation scheme will stimulate further improvements in quality.

3. Introduction
Enthusiastic adoption of the techniques of quality management science, in the form of total quality management systems, will focus future attention on laboratories providing services to the standards dictated by consumers.
Translation of these standards into objective operational specifications will then allow laboratories to adopt appropriate comprehensive quality assurance techniques which will guarantee the quality demanded

4. Quality Assurance of Specimens
Serum or plasma collected by venipuncture or capillary puncture is the sample of choice for the majority of chemical methods
specimen collected without an anticoagulant, producing serum
other methods require that a preservative or anticoagulant be used to
Other tests on other fluids are also ordered
chemical analysis of urine
a limited number of tests are being applied to cerebrospinal fluid and other body fluids
for example, glucose and protein tests
Regardless of the specimen, it should be properly collected, preserved, and transported to the laboratory

5. Quality Assurance of Specimens
Specimens arriving at the laboratory should be labelled so as to provide clear and unambiguous identification.
The identification on the specimen must match that on the request form in all respects.
This verification may be done visually on receipt of the specimen in the laboratory but is best done by use of some form of bar-coding.
Indeed, an approach to the ideal is for the individual who performs specimen collection, in the ward, to scan the bar-coded identification of the patient prepared by the hospital computer or patient administration systems into the laboratory information system and to nominate the tests required.

6. Quality Assurance of Specimen Collection & Transportation
Sodium fluoride
For samples which is necessary to completely stop glycolysis
Urine samples (24 h)
Preservation with boric acid or hydrochloric acid to prevent loss of various metabolites
Transportation of samples to Lab. should be as soon as possible
Some samples should be transported on ice
blood gases (O2 levels decrease while CO2 levels increase)
Some plasma constituents are photosensitive
Bilirubin measurement
Excessive vibration or rough handling
Hemolysis

7. Quality Assurance of Specimen Separation of Serum or Plasma
Once sample is received, it should immediately centrifuged to separate serum or plasma otherwise many changes can occur:
RBCs loose their integrity and intracellular components start to leak
Glucose and O2 concentration decrease
CO2, lactic acid increase while pH becomes more acidic

8. Quality Assurance of Specimen The Effects of Hemolysis
Causes release of RBCs components which will increase the plasma concentrations of:
Plasma Hb
Which will interfere with bilirubin determinations with any measurements made at 540 nm
Potassium
Alanine aminotransferase
Inorganic phosphorus
Copper
Lactate dehydrogenase
Aspartate transaminase
Magnesium
Creatinine Kinase
Acid phosphatase

9. Change in concentration
Quality Assurance of Specimen Changes due to storage of whole blood at RT
Constituent
Change in concentration
Ammonia
Marked increase
Bilirubin
Mild to marked decrease
Total CO2
Carbonic acid
Lactic acid
Magnesium
Mild increase O2
Marked decrease
Glucose
Decreases
Plasma enzymes
Mild to marked decrease in activity
Protein, sodium, chloride, Creatinine, Calcium
Unchanged

10. Sources of Error in Clinical Chemistry
1. Specimen mix-up
A Specimen drawn from wrong patient
Specimen labeled with the wrong name or accession numbers
Serum transferred into mislabeled tubes
Improper cup placed into a tray position and the results reported on the wrong patient
2. Allowing evaporation of a sample while it sits on the analyzer waiting to be analyzed
This will concentrate the sample, resulting in higher values
3. Dilution and calculation errors
Incorrect dilution of sample
Failure to correct for dilution

11. Sources of Error in Clinical Chemistry
4. Sampling errors
Partially clotted specimen
Short sampling
Air bubble in the bottom of the cup
Fibrin clot in the sample probes
5. Transcription errors
6. Instrument losing calibration due to:
dirty reaction cuvettes,
or worn pump tubing;
7. Instrument is not recalibrated when new reagents are placed on the instrument
This can result in a shift in the calibration

12. Quality Assurance of Basic Laboratory Equipment
Many items of basic laboratory equipment are employed in the laboratory and it is important that these are subjected to routine quality assurance
The temperature control of major equipment should be monitored using thermometers or electronic devices.
The performance of spectrometers should be checked for wavelength calibration using colored solutions or didymium or holmium oxide niters; absorbance must also be monitored regularly using colored solutions

13. Quality Control
Internal quality control
External quality control

14. Accreditation of Laboratories
The accreditation system is simple.
A laboratory approaches Clinical Pathology Accreditation (CPA- UK) and receives an application form and handbook.
The handbook acts as a guide to the interpretation of the standards for both inspectors and applicant.
The applicant performs in-house assessment against the standards and fills in the form to show compliance with, or exemption from, each of them.
On receiving the completed forms, an inspection is arranged by the project office at a convenient time for both inspectors and applicant.

15. Accreditation of Laboratories
There are two inspectors for each laboratory, a consultant grade scientist or pathologist and a senior Medical Laboratory Scientific Officer.
Inspectors are trained and appointed by CPA (UK) through its advisory committees.
If problems are identified by the inspectors, accreditation is not granted until the difficulties are resolved to the satisfaction of CPA (UK).
Accreditation is not withheld on the basis of a single inspection, however

16. Accreditation of Laboratories
The standards required are comprehensive and the 44 requirements cover:
organization and administration of the laboratory,
staffing,
facilities and equipment,
policies and protocols,
staff education,
and evaluation of the service.
Many of the standards are concerned with the need for quality assurance methods covering all aspects of laboratory performance.

17. Total Quality Management
A recent trend has been to imitate industry and adopt the beliefs of quality management science to establish total quality management (TQM).
The focus of TQM is continuous improvement of quality.
The first step is to define the needs of the 'customers' of the laboratory which includes:
Clinicians, patients, nurses, administrators, other departments, accreditation inspectors and others.

18. Total Quality Management
The needs of these customers define the quality goals that the laboratory should achieve.
Then the laboratory institutes quality planning to guide the implementation and ongoing monitoring provided by quality control and quality assurance.
When the quality is unsatisfactory, quality improvement should take place which may impinge upon quality plans.