Table 1. Frequency of underlying causes of portal hypertension and mean age for first variceal bleeding in children with portal hypertension.

Underlying causes of portal hypertension	Frequency (%)	Mean age for first variceal bleeding (year)
Cryptogenic cirrhosis	12 (26.7%)	10.1
Biliary atresia	11 (24.4%)	3.3
Wilson's disease	8 (17.8%)	7.5
Congenital hepatic fibrosis	3 (6.7%)	3
Portal vein thrombosis	2 (4.4%)	10.3