<prompt> In neonatal cholestasis, if the serum gamma glutamyl- transpeptidase GGT is more than 600 IUL the most likely diagnosis is:Neonatal hepatitisCholedochal cystSclerosing cholangitisBiliary atresia  <response>: D. Biliary atresiaRef: Nelsons 20e p 19333 Enzymes reflect cholestasis: Alkaline phosphatase, 5nucleotidase Gamma glutamyl transpeptidase.About GGT in Cholestasis: Normal value of GGT is 5-40IULGGT levels are commonly elevated to values more than 10 times normal in biliary atresia while in hepatic causes it is raised to about three times normalThus a value of 600IUL in the patient in question reflects an elevation of more than ten times the normal value. The patient is thus likely suffering from biliary atresia. 