When no better reference is at hand to interpret individual laboratory results, it is the custom to use population-based reference ranges. A better reference, if not from too long ago, would be an earlier result from the same individual (HARRIS u. BOYD, 1990). The animal is classified as abnormal indicating a pathological or unusual situation when the analytical result is outside this reference range. By comparing analytical results from samples obtained serially, it is possible to create an animals own reference range (JENSEN et al., 1992).
With the time all clinical chemistry analytes change. Those changes occur in healthy individuals, just as well as in disease states (FRASER u. HARRIS, 1989). There are many factors contributing to the variability of data, for example the process of measurement, biological variation within each individual and differences among individuals owing to genetic or other factors (COTLOVE et al., 1970). In healthy individuals, laboratory measurements of biochemical parameters consist of intra-individual and inter-individual biological variations (MOSES u.
HENDERSON, 1984). Each individual, living on this planet, is somehow solitary in his enclosed entity and anyhow different amongst the others. It should be treated as a unity, controlled by manifold environmental conditions. The biological variance, as well as the analytical, have a stake in the results of biochemical and haematological blood parameters and should be implied when evaluating labor rest results. The analytical results are being compared to the corresponding population-based reference intervals. The variability of the measured values is often disregarded.
Therefore, it is indespensable to consider each individual as a union.
The use of data on the components of variation, the Index of Individuality (IoI) and the critical difference (CD) permit decisions on diagnosis and treatment of disease. Variations and pathological or unphysiological changes, within the population-based reference ranges, can be detected.
Biological variance / haematology / clinical chemistry / healthy cats / index of individuality / critical difference