Question

Your biological variation? How would this assessment finding enhance your understanding of your patient’s needs?

Answer 1

1. Many analytes of interest in the clinical laboratory can vary over an individual's lifetime, because of natural biological factors involved in the aging process. These variations may be the stages of life cycle, such as during the neonatal period, childhood, puberty, menopause, or old age. Certainanalytes have predictable biological rhythms or cycles. These cycles may be daily, monthly, or seasonal. Knowledge of these cycles is vital for good patient care.

   Variation may be shown in physical appearance, metabolism, fertility, mode of reproduction, behaviour, learning and mental ability, and other obvious or measurable characters.

2. Use of this assessment data derived from biological variation helps to understand

The within and between-subject components of biological variation have been used for many purposes -

To set analytical quality specificationsT

To evaluate the significance of changes in serial results (the reference change value)

To assess the utility of population-based reference values

To assess the number of specimens required to estimate the homeostatic set point.

To assess the best way for reporting results

To select the best specimen (the one with lowest variability)

To compare available tests

To assess the clinical utility of tests

The within- and between-subject components of variation, expressed in coefficients of variation (CVw and CVg, respectively) and the corresponding quality specifications for analytical imprecision (I), bias (B) and total error (TE), expressed in percentages, were calculated according the following formulas:

I < 0.5 CVw

B < 0.25 (CVw2 + CVg2)1/2

TE < k. 0.5 CVw+ 0.25(CVw2 + CVg2)1/2 being k= 1.65 at a=0.05