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[LP-X in newborns: increased incidence of positive tests without cholestasis (author's transl)]
Insights
Abnormal lipoprotein-X (LP-X) is common in newborns, appearing in nearly 50% within weeks, even without cholestasis. This finding suggests immature liver function, not liver disease, in infants.
Area of Science:
- Neonatal Medicine
- Biochemistry
- Pediatric Gastroenterology
Context:
- The presence of abnormal lipoprotein-X (LP-X) in neonatal serum is a poorly understood phenomenon.
- Previous studies have not clearly defined the diagnostic utility of LP-X in newborns.
Purpose:
- To investigate the incidence and significance of lipoprotein-X (LP-X) in newborn infants.
- To determine if LP-X presence correlates with cholestasis or other clinical indicators in neonates.
Summary:
- A study of 194 newborns revealed LP-X in nearly 50% during the first weeks, higher in premature infants (65%), without clinical signs of cholestasis.
- No correlation was found between bilirubin levels, liver enzyme activities, or cholesterol concentrations and LP-X presence.
- LP-X typically appeared after the first day of life and could persist for 2-3 months, indicating it's not a reliable marker for neonatal cholestasis.
Impact:
- The LP-X test is not useful for diagnosing cholestasis in newborns, as it is specific for cholestasis only after one year of age.
- The high incidence of positive LP-X tests in infants likely reflects immature liver function rather than pathological liver conditions.
- This research clarifies the non-diagnostic nature of LP-X in neonates, guiding clinical practice and future research into infant liver development.
Abstract:
The investigation of 194 newborns has shown that during the first weeks of life the abnormal lipoprotein-X (LP-X) was present in the serum of nearly 50% of the infants, with no clinical chemical evidence of cholestasis. The percentage of LP-X positive tests was even higher in the group of immature newborns (65%). There was no correlation between the bilirubin concentration and the detection of LP-X. The activities of leucine arylamidase (EC 3.4.1.1) and gamma-glutamyltransferase (EC 2.3.2.2) as well as the concentrations of total and free cholesterol did not differ in the LP-X positive and negative infants. Except in one case, LP-X was never detectable on the first day of life. The earliest date of appearance was the second day. In the serum of some infants, who were LP-X positive shortly after birth, the lipoprotein could still be found at the age of 2--3 months. The incidence of LP-X was not higher in newborns with blood group incompatibility than in newborns with unspecific hyperbilirubinaemia. After exchange transfusions LP-X disappeared in most cases, but it could later often be detected again. In some newborns, who were LP-X negative a few days after birth LP-X was first detected at the age of 2-3 months. The LP-X test is of no use for th diagnosis of cholestasis in newborn infants. The test is specific for cholestasis only after the first year of life. The increased incidence of positive LP-X tests in newborns is discussed as a consequence of immature liver function.