Reticulocyte count

Keywords: Retics, Retic count

Specimen:

5 mL blood in EDTA tube.

Method:

Fresh blood incubated with:

  1. supravital stain for ribosomal RNA and examined by microscopy; or

  2. fluorescent dye taken up by RNA and cells counted by Flow cytometry.

Most current haematology analysers have reticulocyte modules to perform semi-automated or automated reticulocyte counts. Principle of test depends on the specific instrument.

The absolute reticulocyte count is calculated from the reticulocyte percentage and the red cell count.

Reference Interval:

Refer to laboratory. Term infant, cord blood: 2-6%  (microscopy)

Child, adult:     

0.2-2.0% (10-100 x 109/L)  (microscopy)

0.7-3.2% (30-140 x 109/L)  (flow cytometry).

Application:

Indicated in the assessment of anaemia when bone marrow failure or haemolysis suspected;

apparent inadequate marrow response to haematinic therapy;

assessment of recovery after myelosuppression; and

monitoring haemolytic anaemia.

Interpretation:

Reticulocyte count reflects marrow erythropoietic activity and corresponds to the finding of polychromasia on a blood film.

A low reticulocyte count in the presence of anaemia generally indicates bone marrow failure or haematinic deficiency.

Reference:

Bain et al. Dacie and Lewis Practical Haematology. 11th Ed. 2012.