Clarify the different characteristics of erythrocytosis

Erythrocytosis without JAK2 mutation has various causes, and this patient population includes both patients with and without polycythemia vera (PV). A study published in the European Journal of Internal Medicine compared the characteristics of patients with erythrocytosis and PV versus those without PV.

The study included adult patients with JAK2-unmutated erythrocytosis according to tests performed between 2016 and 2019. Hemoglobin thresholds for PV were 16.5 g/dL in men and 16 g/dL in women, and hematocrit thresholds were 49% and 48% in men. and women, respectively. This is consistent with the WHO criteria for the diagnosis of PV as of 2016. Hemoglobin thresholds for absolute erythrocytosis were 18.5 g/dL in men and 16.5 g/dL in women, and hematocrit thresholds were 55.5% for men and 49.5% for women. .

There were 1145 JAK2-unmutated patients with erythrocytosis identified during screening, the majority of whom had no diagnosis at the time of the study. “This may reflect a lack of exploration or could call into question the appropriateness of erythrocytosis thresholds as defined by the 2016 WHO for our coastal population,” the authors noted.

A total of 525 patients without JAK2 mutation were included in the analysis, and 69 individuals with JAK2 mutated PV were included for comparison. The median age of patients was 58 years and 90.3% of patients were male. High blood pressure, venous thromboembolism, obesity, ischemic heart disease, diabetes, stroke, and sleep apnea were the most common comorbidities. The main clinical signs in non-JAK2 mutated patients were symptoms similar to sleep apnea, headache, deterioration of general condition, facial erythrosis, fatigue and pruritus.

The reference treatment for PV in this cohort was phlebotomy. For patients at high risk of thrombosis, cytoreductive therapy may be considered. Low-risk patients may benefit from low-dose aspirin. In non-PV patients, treatment tends to be more case-by-case, although the authors note that current research suggests a goal of symptom relief over hematocrit reduction.

Overall, the data suggest several notable clinical and biological differences between PV and non-PV patients. Overall, non-PV patients were younger than PV patients (56 years versus 66 years) and were more often male (69.1% versus 90.3%, P <.001 patients with pv were more often obese versus>P = 0.023) and showed an overall deterioration in health compared to non-PV patients (19.8% vs 5.7%, P <.001 they were also more likely to suffer from facial erythrosis pruritus splenomegaly and erythromelalgia.>

Hematological measurements also differed between the groups. Patients with PV reached the absolute erythrocytosis threshold more often than patients without PV (54.3% versus 16.8%, P <.001 pv patients also showed higher hematocrit white blood cell count neutrophil and platelet compared to non-pv patients. lymphocyte eosinophil basophil were lower in than erythropoietic titers>

“Distinctive characteristics between patients with polycythemia vera could lead to the establishment of a predictive PV score for better selection of non-mutated JAK2 patients at high risk of PV eligible for bone marrow biopsy,” write the authors. authors.

A major concern is the lack of clear diagnoses in JAK2 unmutated erythrocytosis, as well as the lack of consensus on therapeutic approaches. With a selection of known causes that have specific treatments, identifying the underlying cause of erythrocytosis can prove useful in cases where it is secondary to another condition.


Ernest V, Abbou N, Tichadou A, Arcani R, Venton G. Characteristics of JAK2 unmutated erythrocytosis: distinctive features between patients with polycythemia vera and patients without polycythemia vera. Eur J Case Rep Intern Med. Published online September 10, 2022. doi:10.1016/j.ejim.2022.09.004

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