5.3. The statistical evaluation of reference values

It consists of [6]:

Considering the reference interval that accrues to therapeutic drug levels, a "normal" individual will not have any drug dominating his/her system, while a patient undergoing therapy exhibits a certain target range. The theory of developing reference intervals involves standardization of collection approaches, application of statistical techniques in analyzing reference values, and selection regarding reference populations. There are two key forms of reference interval examinations—verification of reference interval and establishment of reference intervals. Establishment of a reference interval prevails once there lacks an existing analyte or rather methodology regarding the reference or clinical lab entitled to hold the comparative studies. This approach is labor intensive besides being costly since it entails lab resources at nearly all levels and may call for 120–700 study persons. Nonetheless, verification of a reference interval, or rather transference, is done with an aim of confirming the validity accruing to a prevalent reference interval provided that the analyte is utilizing identical analytic systems (methodology and/or instrumentation). This approach is fairly common regarding the operation of the clinical labs and can call for a few study individuals like 20. In addition to that, application of reference interval can be categorized into three primary classes—diagnosis of a condition or disease, monitoring a physiologic condition, and therapeutic management. The paradigm for verification or establishment of reference intervals can be damn overwhelming notably for the clinical lab that deals with multiple degrees of reference intervals-partitions. The personnel, resource, and cost requirements necessitate that the underlying reference interval examination ought to be well structured and defined to yield timely and accurate reference intervals for the

This identification of people worth of inclusion in a certain reference interval experiment necessitates definition of detailed exclusion/inclusion criteria. The inclusion criteria state the factors crucial for use in the study, whereas the exclusion criteria specify the factors that make persons inappropriate for the experiment. Selection of the right individuals facilitates the acquisition of optimal specimens that exhibit acceptable degrees of confidence. Moreover, collecting the appropriate information regarding the exclusion and inclusion criteria, like donor health status, frequently necessitates a well-documented and confidential questionnaire as well as a consent form. An additional consideration regarding the selection of the individuals encompasses additional determinants that may necessitate partitioning persons into sub-

After selection of individuals for a specific reference interval examination, a key consideration entails the pre-analytic and analytic variables capable of influencing certain lab tests. Control and standardization of both variables are crucial for the generation of valid reference intervals. Additionally, some approaches are damn sensitive to interferences. For instance, mass spectrometry is resistant to interferences, while chemical approaches are sometimes highly sensitive to the same. Additional consideration entails the specific reagents used since altering to a modern agent amidst a reference examination can widen the underlying reference interval or rather transform the data distribution, maybe from bimodal to normal. Universally, a valid

groups. Such subgroups may need separate reference interval experiments.

productive clinical application.

14 Quality Control in Laboratory

5.1. Selection of reference interval study persons

5.2. Pre-analytic and analytic considerations

