Is the hematocrit still an issue in quantitative dried blood spot analysis?

Hematocrit-related issues remain a major barrier for (regulatory) acceptance of the classical dried blood spot (DBS) analysis in the bioanalytical and clinical field. Lately, many attempts to cope with these issues have been made. Throughout this review, an overview is provided on new strategies that try to cope with this hematocrit effect (going from avoiding to minimizing), on methods estimating a DBS volume, and on methods estimating or measuring the hematocrit of a DBS. Although many successful strategies have been put forward, a combination of different technologies still provides the most complete solution. Therefore, further efforts and the availability of a straightforward guideline for analytical and clinical method validation should help to overcome the hurdles still associated with DBS sampling.