Back to the “Gold Standard”: How Precise Is Hematocrit Detection Today?

Abstract

Introduction: The commonly used method for hematocrit detection, by visual examination of microcapillary tube, known as "micro-HCT", is subjective but still remains one of the key sources for false hematocrit evaluation. Analytical automation techniques have increased standardization of RBC indexes detection; however, indirect hematocrit measurements by blood analyzer, the automated HCT, does not correlate well with "micro-HCT" results in patients with hematological pathologies. We aimed to overcome those disadvantages in "micro-HCT" analysis by using "ImageJ", processing software.
 Methods: 223 blood samples from the "general population" and 19 from sickle cell disease patients were examined in parallel for hematocrit values using the automated HCT, standard "micro-HCT" and "ImageJ" micro-HCT methods.
 Results: For the "general population" samples, the "ImageJ" values were significantly higher than the corresponding values evaluated by standard "micro-HCT" and automated HCT, except for the 0 to 2 months old newborns, in which the automated HCT results were similar to the "ImageJ" evaluated HCT. Similar to the "general population" cohort, we found significantly higher values measured by "ImageJ" compared to either "micro-HCT" or the automated HCT in SCD patients. Correspondent differences for the MCV and MCHC were also found.
 Conclusions: This study introduces "micro-HCT" assessment technique using the image-analysis module of "ImageJ" software. This procedure allows overcoming most of the data errors associated with the standard "micro-HCT" evaluation and can replace the use of complicated and expensive automated equipment. The presented results may be also used to develop new standards for calculations of hematocrit and associated parameters for routine clinical practice.