Reference change values: how useful are they?

Abstract

A simple comparison between two sequential results is not as straightforward as it seems. It should be remembered that each result is associated with its own inherent random variation, meaning that each result obtained is, in fact, a dispersion rather than a singular value. This random variation comprises both variation associated with laboratory activity (pre-analytical and analytical variation) and inherent biological variation (intra-individual) (see box 1).