Compared with patients with PV, MPN suspects had significantly lower odds of a MCV less than 82 (odds ratio [OR], 0.16; 95% CI, 0.038-0.068) or a serum ferritin less than 15 µg/L (OR, 0.2; 95% CI, 0.52-0.74). No patients with ET had a MCV less than 82 or a ferritin level less than 15 µg/L.

In commenting on this finding, the study authors noted that the “hematocrit value must be interpreted carefully when being used for diagnosis of PV in patients with microcytosis.”

When patients with microcytosis were excluded from the analysis, the hemocrit levels and RBC counts were well correlated in both PV patients and MPN suspects. However, when patients with microcytosis were included, R2 values were 0.41 for those in the PV group compared with 0.66 for MPN suspects and 0.81 for patients with ET.

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Regarding ESR, at a cutoff value of 2 mm separating positive (<2 mm) and negative (≥2 mm) ESR tests, the sensitivity and specificity for distinguishing patients with PV from MPN suspects were 37.1% and 97.7%, respectively.

The study authors noted that prospective trials are needed to validate the usefulness of RBC count and ESR as diagnostic biomarkers for PV.

Reference

Nersesjan V, Zervides KA, Sørensen AL, et al. The red blood cell count and the erythrocyte sedimentation rate in the diagnosis of polycythaemia vera. [published online October 4, 2019]. Eur J Haematol. doi: 10.1111/ejh.13334

This article originally appeared on Oncology Nurse Advisor