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Pseudodeficiency of glutamine in infant liver disease

T Vermeulen1, T Marquardt, J Häberle

  • 1Klinik und Poliklinik für Kinder- und Jugendmedizin, Universitätsklinikum Münster, Albert-Schweitzer-Strasse 33, 48129 Münster, Germany.

Amino Acids
|July 25, 2008
PubMed

Insights

Elevated gamma-glutamyltransferase (gamma-GT) in infants can falsely lower serum glutamine levels, mimicking a deficiency. Physicians should notify labs of high gamma-GT to prevent misdiagnosis.

Area of Science:

  • Biochemistry
  • Clinical Chemistry
  • Pediatric Medicine

Background:

  • Gamma-glutamyltransferase (gamma-GT) is a key enzyme in amino acid metabolism.
  • Elevated serum gamma-GT is an established early indicator of cholestasis.
  • Gamma-GT possesses glutamine-deamidating activity.

Purpose of the Study:

  • To investigate the effect of elevated gamma-GT on serum glutamine levels in infants.
  • To determine if increased gamma-GT activity can lead to a pseudodeficiency of glutamine.
  • To analyze the time-dependent changes in glutamine and glutamate concentrations.

Main Methods:

  • Serum samples from infants with elevated gamma-GT were analyzed.
  • Time-course studies were conducted to measure glutamine and glutamate concentrations.
  • In vitro experiments assessed the impact of gamma-GT on glutamine deamidation.

Main Results:

  • Infants with elevated serum gamma-GT exhibited decreased serum glutamine levels.
  • Time-dependent studies showed a significant drop in glutamine below normal limits.
  • Concurrently, glutamate levels increased above normal upper limits.

Conclusions:

  • Increased gamma-glutamyltransferase activity in vitro can induce a pseudodeficiency of serum glutamine.
  • Physicians must inform clinical laboratories about accompanying pathologies like elevated gamma-GT to avoid diagnostic errors.
  • Accurate interpretation of serum glutamine levels requires consideration of concurrent gamma-GT activity.

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