In a child presenting with obstructive Jaundice, all are seen except –: (A) Gamma glutamyl transpeptidase, (B) Alkaline phosphatase, (C) Glutamate dehydrogenase, (D) 5' Nucleotidase
Answer is C. Neonatal cholestasis 

Neonatal cholestasis is defined as prolonged elevation of serum levels of conjugated bilirubin beyond the first 14 days of life.
Neonatal cholestasis can be divided into extrahepatic and intrahepatic disease and clinical features of any form of cholestasis are more or less similar.
Neonatal hepatitis is the prototype of intrahepatic cholestasis
Biliary atresia is the prototype of extrahepatic biliary atresia

Enzymes that reflect cholestasis: There are three enzymes that are usually elevated in cholestasis

Alkaline phosphatase → Found in or near bile canalicular membrane of hepatocytes
5' nucleotidase
Gamma-glutamyl transpeptidase → Located in the endoplasmic reticulum and in bile duct epithelial cells.


Because GGT is more diffusely localized in the liver, its elevation in serum is less specific than are the elevation of Alkaline phosphatase & 5' nucleotidase.
Nevertheless, the following distinction is worthwhile.

"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 5-40 IU/L and thus a value of 600 IU/L 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'.