The RET channel delivers a valuable contribution to anaemia diagnosis. The appropriate combination of parameters highlights the complete picture of erythropoiesis and its further development.

In cases of interferences with red blood cells and their associated parameters such as the MCHC, there is a new optical ‘CBC-O’ algorithm embedded in the Extended IPU. It delivers conclusive information about the cause of interference, suggests replacement of the affected parameters with their counterparts from the RET analysis and automatically recalculates the RBC indices. Using the RET channel together with CBC-O reduces the need for laborious manual testing of such samples.

RET-He is a diagnostic advanced clinical parameter that is derived from the RET channel. It has proven its diagnostic efficiency of being superior to all mature red blood cell related parameters.

How it works

In the RET channel, the lysis reagent slightly perforates the cell membranes of red blood cells, white blood cells and platelets and so allows the fluorescence marker to penetrate the cell. The fluorescence marker labels the intracellular nucleic acids whereby the intensity of the resulting fluorescence signal is directly proportional to the nucleic acid content.
Using the forward scattered light and the fluorescence signal, the reticulocytes can be separated from mature red blood cells.

According to their fluorescence intensity, reticulocytes are fractionated into three categories, representing different stages of maturity:

LFR (low fluorescence reticulocytes)
MFR (medium fluorescence reticulocytes)
HFR (high fluorescence reticulocytes)

The IRF (immature reticulocyte fraction) reflects the proportion of immature reticulocytes and is calculated from the sum of MFR plus HFR. IRF is an indicator of erythropoiesis and correlates well with the engraftment of neutrophils as published by researchers.

The RET channel also provides the optical platelet count (PLT-O) as they also contain intracellular RNA. Automated reflex measurement is implemented for samples with unreliable PLT-I counts since the use of fluorescence flow cytometry resolves many PLT-I interferences that are based on size.

Sysmex Scattergram of the RET channel with a normal cell distribution — Scattergram of the RET channel with a normal cell distribution