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The third type of variation we will look at is Biological Variation (BV).
Biological Variation is the naturally occurring fluctuations or variations in the concentration
of an analyte through time and naturally occurring conditions.
The homeostatic setting point is the value in an individual around which this variation
occurs.
The third type of variation we will look at is Biological Variation (BV).
Biological Variation is unique to each individual and to each analyte.
Biological Variation data is collected during highly controlled experiments using native
human serum, plasma, whole blood or urine.
Data collected during these experiments can be one of two types of Biological Variation:
With-in subject - the average inherent Biological Variation around the homeostatic setting point
of a group of average individuals.
Between subject - the variation between the homeostatic setting points of individuals.
Biological Variation is expressed as a Coefficient of Variation percent (CV %).
Use CVw to express with-in subject Biological Variation. CV is the coefficient of variation
and the w indicates with-in subject.
Use CVb to express between subject Biological Variation. CV is the coefficient of variation
and the b indicates between subjects.
As mentioned before, collection of Biological Variation data is through controlled studies.
The areas that are controlled are: Population, Specimen, Analysis.
Participants in these studies must adhere to a strict schedule and lifestyle. For instance,
they may not be able to eat or drink anything with caffeine for the duration of the study.
In addition, they must be available for sample collection on specific dates and times over
a period that can last for days or even weeks.
Maintaining specimen integrity by keeping specimen collection, transport and pretreatment
processes consistent is crucial.
The timing of collection is particularly important for analytes that exhibit documented patterns
of change based on Circadian rhythms, sleep/wake cycles, monthly cycles and season rhythms.
As previously mentioned in this course, transport of the specimen in a timely manner and at
the correct temperature is important in preserving specimen integrity.
Lastly, during the analysis of the specimen, it is important to eliminate all components
of Analytical Variation. When this is accomplished, the variation measured should be biological
and not analytical.
Consistency of instrument, operator, reagent lot number(s), calibrator lot number and testing
environment reduces the risk of introducing Analytical Variation.
Biological Variation is the fluctuation in concentration of an analyte through time and
naturally occurring conditions.
Biological Variation is unique to each person and analyte.
Biological Variation is expressed as CV%.
There are two types of Biological Variation: with-in subject (CVw) and between subject
(CVb).
With-in subject Biological Variation is the inherent Biological Variation around the homeostatic
setting point of a group of average individuals.
Between subjects Biological Variation is the variation between the homeostatic setting
points of individuals.
Highly controlled experiments using native human serum, plasma, whole blood or urine
is how to obtain Biological Variation data.