Prevalence of paroxysmal sleep nocturnal hemoglobinuria in patients with Buga’s syndrome or portal vein thrombosis in China Background and aim: In Western countries, routine screening for paroxysmal sleep hemoglobinuria (PNH) is recommended in patients with Buga’s syndrome (BCS) or portal vein thrombosis (PVT). However, little is known about the need for this routine screening in Chinese patients with BCS or PVT. We conducted a prospective observational study to examine the prevalence of PNH in this group of patients. Methods: Patients with primary BCS or non-malignant PVT admitted to our center from September 2009 to December 2011 and followed up regularly were enrolled in this study, and the expression of CD55 or CD59 on erythrocytes and granulocytes was measured in these patients. PNH was diagnosed by flow cytometry assay showing both CD55 and CD59-deficient clones of peripheral blood mononuclear cells. Results : CD55 and/or CD59 defects were found in 1.6% (2/127) of patients with primary BCS, 1.0% (1/100) of patients with non-malignant and non-cirrhotic PVT, and 4.7% (4/85) of patients with cirrhotic PVT. Only one patient was found to have both granulocyte CD55 and CD59 defects, but this patient had a confirmed diagnosis of PNH before the diagnosis of BCS. Conclusion : PNH is very rare in Chinese patients with BCS or PVT, suggesting selective screening for PNH in these patients.