[Characteristics of diagnostic approach to erythrocytosis of different genesis]

To show distribution of the investigated patients into diagnostic groups, find out the diagnostic value of the levels of hemoglobin and packed cell volume as possible markers of absolute erythrocytosis in the group of patients with polycythaemia.

We evaluated 61 patients, mean age was 46 years (18-82), 9 females and 52 males before treatment. Mean levels of hemoglobin in females - 171 g\l (143-190), packed cell volume 52% (49-61). Mean levels of hemoglobin and packed cell volume for males were 187 g/l (168-196) and 57,8% (49-65), respectively. All blood samples were taken in the morning. Full blood picture of venous blood was determined by Coulter principle on Gen S ("Beckman-Coulter", USA) blood analyzer with preserving agent (ethylene diamine tetraacetate, EDTA). Red cell mass and plasma volume were measured by the radionuclide method (Cr-51). Results were performed with an allowance for patient's surface area and were interpreted according to International Council for Standardization in Haematology guidelines (ICSH) (Pearson et al. 1995).

Polycythaemia vera was detected only in 19 (31%) among 61 patients, 15 patients refused from further investigation. Among others 46 patients 14 subjects had secondary erythrocytosis, among them 9 were diagnosed with absolute erythrocytosis (hypoxic) and 5 with idiopathic erythrocytosis. Relative ("apparent") erythrocytosis was detected in 13 cases. Measurement of red cell mass allowed us to divide patients into groups with absolute and relative erythrocytosis. Such laboratory parameters as hemoglobin, number of red blood cells and packed cell volume do not always completely show the level of red cell mass due to possible variations of the plasma volume and can not be the reason for diagnosis of haematological disorder. It is shown that hemoglobin level over 185 g/l confirms the presence of absolute erythrocytosis only in 50% of males with polycythaemia, 15% of males with secondary erythrocytosis might have incorrect diagnosis as though increased red cell mass. Statistically defined highly significant (p=0,001) difference of the level of red cell mass in males with polycythaemia and patients with "apparent" polycythaemia turned out to 166% and 111%, respectively. The levels of red cell mass in patients with polycythaemia confirm absolute erythrocytosis over superior normal limit (more then 25%) in comparison with secondary erythrocytosis where red cell mass rate remained normal. Average plasma volume measurements in the same groups of patients were at normal range - 95% u 81%, respectively. Difference between these mean values was authentically significant.

Red cell mass and plasma volume measurement is easy and necessary procedure for estimation absolute and "apparent" polycythaemia. Rather common occurrence of different forms of erythrocytosis and in particular "apparent" erythrocytosis must determine certain diagnostic approach according to specific clinical case.