BACKGROUND AND AIM: Routine screening for paroxysmal nocturnal hemoglobinuria 
(PNH) in patients with Budd-Chiari syndrome (BCS) or portal vein thrombosis 
(PVT) has been recommended in Western countries. However, little is known about 
whether the routine screening test should be necessary in Chinese patients with 
BCS or PVT. We conducted a prospective observational study to examine the 
prevalence of PNH in these patients.
METHODS: Patients with primary BCS or non-malignant PVT who were consecutively 
admitted to our department or regularly followed up between September 2009 and 
December 2011 were eligible for the study and detected the expression of CD55 
and CD59 on erythrocytes and granulocytes. The CD55 or CD59 deficiency was 
considered as the proportion of erythrocytes or granulocytes with normal 
expression of CD55 or CD59 was less than 90%. PNH was diagnosed by both CD55 and 
CD59 deficient clone at flow cytometry of peripheral blood cells.
RESULTS: CD55 and/or CD59 deficiencies were found in 1.6% (2/127) of patients 
with primary BCS, 1.0% (1/100) of non-malignant and non-cirrhotic patients with 
PVT, and 4.7% (4/85) of cirrhotic patients with PVT. Only one patient had both 
CD55 and CD59 deficiencies on granulocytes. But he had been diagnosed with PNH 
before BCS.
CONCLUSIONS: Paroxysmal nocturnal hemoglobinuria was very rare in Chinese 
patients with BCS or PVT, suggesting that routine screening for PNH should not 
be indiscriminately performed in such patients.