[LP-X in the first month of life (author's transl)].

An abnormal lipoprotein can be detected in the sera of patients suffering from intra- and extrahepatic cholestasis. The specificity of LP-X detection for the diagnosis of cholestasis in adult persons was proved by extensive investigations. The aim of this study was to examine the specificity of LP-X with regard to cholestasis in the postnatal phase of premature and newborn infants. 1056 sera of 270 newborns were tested and in 75% of these cases LP-X was found to be positive. Three hypothetical explanations are given concerning the appearance of LP-X in the sera of premature and newborn infants. The semi-quantitative determination of LP-X also represents a possibility for differential diagnosis of obstructive jaundice in the neonatal period.