<prompt> In neonatal cholestasis, if the serum gamaglutamyl-transpeptidase gamma GTP is more than 600IUL the most likely diagnosis is:Neonatal hepatitisCholedochal cystSclerosing cholangitisBiliary atresia  <response>: GGTP of more than 600IUL is suggestive of cholestasis. GGT 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 normal. Normal values for GGT is about 5-40IUL. Ref: Harrisons Principles of Internal Medicine, 17th Edition, Page 1998 ; O P Ghai Essential Pediatrics, 6th Edition, Page 174 ; Surgery of Liver, Bile Duct and Pancreas in Children By Edward Howard and Stringer 2nd, Page 112 ; Liver Disorder in Childhood By Alex P. Mowat 