Screening of newborn infants for cholestatic hepatobiliary disease with tandem mass spectrometry

Objective To assess the feasibility of screening for cholestatic hepatobili ary disease and extrahepatic biliary atresia by using tandem mass spectrome try to measure conjugated bile acids in dried blood spots obtained from new born infants at 7-10 days of age for the Guthrie test. Setting Three tertiary referral clinics and regional neonatal screening lab oratories. Design Unused blood spots from the Guthrie test were retrieved for infants presenting with cholestatic hepatobiliary disease and from the two cards st ored on either side of each card from an index child. Concentrations of con jugated bile acids measured by tandem mass spectrometry in the two groups w ere compared. Main outcome measures Concentrations of glycodihydroxycholanoates, glycotri hydroxycholanoates, taurodihydroxycholanoates, and taurotrihydroxycholanoat es. Receiver operator curves were plotted to determine which parameter (or combination of parameters) would best predict the cases of cholestatic hepa tobiliary disease and extrahepatic biliary atresia. The sensitivity and spe cificity at a selection of cut off values for each bile acid species and fo r total bile acid concentrations for the detection of the two conditions we re calculated. Results 218 children with cholestatic hepatobiliary disease were eligible f or inclusion in the study. Two children without a final diagnosis and five who presented at < 14 days of age were excluded. Usable blood spots were ob tained from 177 index children and 708 comparison children. Mean concentrat ions of all four bile acid species were significantly raised in children wi th cholestatic hepatobiliary disease and extrahepatic biliary atresia compa red with the unaffected children (P < 0.0001). Of 177 children with cholest atic hepatobiliary disease, 104 (59%) had a total bile acid concentration > 33 mu mol/l (97.5th centile value for comparison group). Of the 61 with ext rahepatic biliary atresia, 47 (77%) had total bile acid concentrations > 33 mu mol/l. Taurotrihydroxycholanoate and total bile acid concentrations were the best predictors of both conditions. For all cholestatic hepatobiliary disease, a cut off level of total bile acid concentration of 30 mu mol/l gave a sensi tivity of 62% and a specificity of 96%, while the corresponding values for extrahepatic biliary atresia were 79% and 96%. Conclusion Most children who present With extrahepatic biliary atresia and other forms of cholestatic hepatobiliary disease have significantly raised concentrations of conjugated bile acids as measured by tandem mass spectrom etry at the time when samples are taken for the Guthrie test Unfortunately the separation between the concentrations in these infants and those in the general population is not sufficient to make mass screening for cholestati c hepatobiliary disease a feasible option with this method alone.