Background: Post-transplant erythrocytosis (PTE) is characterized by persistent hematocrit level above 51% that develops in 10-20% of kidney recipients, mostly 2 years after kidney transplantation. PTE is self limited in 25% of the patients but can be persistent in other patients with an increased susceptibility for thrombosis. The purpose of this study was to identify the risk factors for development of PTE in our center

Methods: We selected 45 patients who were transplanted at least 3 months before selection (minimum time required for detection of PTE) and were referred to the kidney transplantation clinic during 5 years (1998-2003) as the case group. At the same time, we considered 2 patients without erythrocytosis as control for each patient in the case group among kidney transplant recipients who were referred to the same clinic during 5 years (1998-2003). In total we had selected 135 patients, 45 patients with erythrocytosis as the case group and 90 patients without erythrocytosis as the control group. Patients who were affected by high hematocrit before transplantation (HC>51%),overt pulmonary disorder, and polycytemia Vera were excluded from this study. We collected basic information by using old charts and complementary information was added through phone conversations and physical examination in the clinic. All the information was entered in the digital questionnaire and was analyzed by the SPSS statistical package.

Results: There was no significant difference between the case and control group for age, history of hypertension, diabetes, pretransplant hematocrit, pretransplant transfusions, function of graft and source of kidney. A significantly higher proportion of PTE patients were male, also the case group had a significantly higher frequency for personal history of polycystic kidney disease , glomerulonephritis and higher frequency of azathioparine, prednisolone and cyclosporine regimen.

Conclusion: PTE is an important complication of kidney transplantation that can be fatal. There are multiple risk factors that should be addressed to prevent this complication.