Congenital porto-left renal venous (PRV) shunt was found to be the cause of
galactosaemia in four galactosaemic neonates detected by mass screening (P
aigen method). The patients did not have hereditary galactosaemias and were
diagnosed as having galactosaemia of unknown cause, because porto-systemic
venous (PS) shunts had not been recognized. At the time of diagnosis, hype
rgalactosaemia was not severe (0.44-0.55 mmol/L; 8-10 mg/dl) and plasma con
centration of total bile acids (TBA) did not suggest a PS shunt (46-50 mu m
ol/L). However, slightly but consistently increased concentrations of galac
tose and TBA strongly suggested the presence of a PS shunt, and careful ult
rasonographic investigation revealed PRV shunt. We conclude that PRV shunt
should be suspected in patients with hypergalactosaemia of unknown cause.