Determining level of endogenous serum erythropoietin for differential diagnosis of polycythemia vera and symptomatic polycythemia

Abstract

The article deals with determining possibility of the assessment of the level of endogenous serum erythropoietin (EPO) for differential diagnosis of polycythemia vera (PV) and secondary erythrocytosis (SE). The determination of subnormal level of this cytokine for the diagnosis of PV has been detected. The relation between the level of endogenous erythropoietin and iron metabolism also has been analyzed. The study involved 88 patients with PV and 119 patients with SE. Statistically significant decrease in EPO concentration level has been detected in PV patients. The mean EPO level was equal to 6.38 ± 0.84 mIU/mL and 17.98 ±2.48 mIU/mL in PV and SE patients respectively. In control group of individuals EPO concentration was equal to 9,81 ±0,58 mIU/mL, the significant difference was found between all studied groups (р<0.01). According to our data, EPO was increased in 28 SE patients (23.53%), it was not observed in control group and in group of PV patients (φ*emp = 4.355, р<0.01). The decrease of EPO level in PV patients has been detected more often than in SE patients (84.09% versus 11.76% , φ*emp = 5.218, р<0.01), it has not been observed in control group. Only 14 (15.91%) PV patients had normal EPO level, in contrast 77 (64.71%) SE patients demonstrated normal EPO level (φ*emp = 4.578, р<0.01). The average level of ferritin was equal to 57.41 ± 9.74 ng/mL in PV patients and 199.77 ± 14.32 ng/mL in SE patients (р<0.01). Significantly more patients with PV demonstrated decrease of ferritin level (31.81% versus 7.56%, φ*emp = 4.438, р<0.01). Patients with SE more often had raised level of EPO than PV patients (15.12% versus 4.54%, φ*emp = 2.453, р<0.01). The sensitivity of test with detecting of the reduced level of EPO for the diagnosis of PV was 84.1%, specificity - 87.4%, positive predictive value - 83.1%, negative predictive value - 88.1%. Normal range of EPO significantly (rs = 0,5494) correlated with decreased levels of serum ferritin in patients with polycythemia vera, which was caused by iron deficiency in a certain number of patients with PV.