[A 53-year-old man with headache and concentration difficulties]

Polycythaemia vera is a chronic myeloproliferative disease with no single diagnostic marker. The Polycythaemia Vera Study Group used a combination of major and minor diagnostic criteria. In the presence of newer diagnostic tools, low serum erythropoietin level has been proposed as an important diagnostic criterion for polycythaemia vera, whereas an elevated erythropoietin value contradicts the diagnosis. We report a case of polycythaemia vera with extreme haemoconcentration in which the serum level of erythropoietin was above the upper reference limit.

A 53-year-old man with erythrocytosis (packed cell volume 0.68, hemoglobin 23.6 g/dl), thrombocytosis, leukocytosis and no underlying disease had a serum level of erythropoietin of 29.0 U/l (normal range 1.3-21.5 U/l).

The patient was treated with venesection. After one month the haemoglobin level had decreased to 15.7 g/dl and packed cell volume to 0.48. The symptoms of polycythaemia disappeared and the serum level of erythropoietin declined to low normal values (2.2 U/l after five weeks and 5.4 U/l after 1.5 year). We propose that local hypoxia in the kidneys might be responsible for the elevated erythropoietin value at the time of diagnosis. The present case shows that high erythropoietin values may not necessarily exclude the diagnosis of polycythaemia vera.