A voluminous literature attests to the difficulty of diagnosis in jaundice of unknown origin in the neonatal period. For this time of life the history, physical examination, and available laboratory techniques often provide inadequate, and even misleading, information for arriving at a correct etiological diagnosis. This is in contrast to what occurs in older children and adults, in whom these same diagnostic procedures usually suffice to establish the cause of jaundice. Thus, a technique which could significantly help in clarifying the clinical picture in the newborn infant would be an important diagnostic tool in the differential diagnosis of neonatal jaundice.
Measurement of transaminase activity in serum has proved of value in diagnosis of liver disease in children and adults.1-7 For these older age groups alterations in transaminase activity in serum in pathological states have been well documented. However, for the neonatal period and early infancy, apart from our own