Basic Concepts in Clinical Biochemistry-A Practical Guide.7z

calibrators that have expired, sampling errors, and changes in analyzer’s measuring
unit.Post-analytical errorsarise during transmission of data from analyzers, result
validation, and dispatching/communicating results to physicians or patients. Com-
mon post-analytical errors are loss of the results, inappropriate specimen or antico-
agulant, error in storage of sample, or mistakes in patients’identification.

3.2 Methods to Minimize the Laboratory Errors..............

The routinely used methods being performed in a laboratory should be monitored
continuously for any change in precision or accuracy. The quality control techniques
must be used regularly to detect such changes and to follow corrective measures. It is
always desirable that both random and systematic errors must be detected at the
earliest possible stage and preventive measures should be applied to minimize them.
The procedure adopted for the detection of errors consists of specific quality
control methods. Such methods can be divided in two categories:

Internal Quality Control The internal quality control involves internal processes
followed for monitoring of experimental protocols and checking of the resultant data
systematically. Internal quality control mechanism is necessary to reach the conclu-
sion that processed data is reliable enough to be released. In other words, it correlates
the day-to-day quality control methods with the equipment and methods used in the
laboratory. The process predicts about the precision and accuracy of the method
being followed. This process also involves construction of Levey-Jennings chart and
quantification of unavoidable laboratory data (Fig.3.1).

The internal quality control considers the following points:

1. The correlation of clinical test being used with the diagnosis of disease.


2. The analysis of the same sample should be performed two times, and identical
   results must be obtained if no error exists.


3. The reproducibility of samples must be checked frequently.

+3s

+2s

+1s

-1s

-2s

-3s

CL

Fig. 3.1Levey-Jennings
chart with a random error and
a systematic error

3.2 Methods to Minimize the Laboratory Errors 11