Correlation Engine 2.0
Clear Search sequence regions

  • berlin (1)
  • boston (1)
  • Crea (4)
  • enzymes (1)
  • humans (1)
  • LDH (11)
  • native (1)
  • Sizes of these terms reflect their relevance to your search.

    Evaluation of the simultaneous measurement of urinary γ-glutamyltransferase (γGT) and lactate dehydrogenase (LDH) to discriminate fresh from previously frozen specimens in urine drug monitoring. Two widely available photometric tests (Siemens Healthineers Atellica) were used to determine the range of urinary γGT and LDH excretion and to study the decay in urinary enzyme activity under various storage conditions (room temperature, 4-8 °C, -18 °C, -80 °C). From these data, cut-off values were established and evaluated in split (fresh/frozen) specimens. Both assays allow robust, reliable, and simultaneous determination of urinary γGT and LDH. In healthy subjects, the 95% reference intervals for enzyme activity in native urine were γGT: 24.4-100.4 U/g Crea (creatinine) and LDH: 2.5-45.8 U/g Crea. Frozen storage for at least 7 days at -18 °C resulted in a loss of activity to less than 50% in both enzymes. Cut-offs for frozen samples were γGT≤33.2 U/g Crea and LDH≤ 8.4 U/g Crea. When applied to 100 sample pairs (fresh/frozen), 86.5% (173/200) of the measurements were conclusive and the combination of concordant enzyme measurements (low γGT/low LDH or high γGT/high LDH) was able to predict the mode of storage with a sensitivity of 96.3% and a specificity of 96.7%. The additional measurements of urinary γGT and LDH can be used to detect previously frozen urine specimens. A simple protocol is proposed to provide additional information on sample quality when deceit is suspected. The procedure can be easily integrated into the standard workflow of urinary drug monitoring. © 2022 Walter de Gruyter GmbH, Berlin/Boston.


    Anna Friess, Ulrich Friess, Maria Shipkova, Eberhard Wieland. Assessment of urine sample quality by the simultaneous measurement of urinary γ-glutamyltransferase and lactate dehydrogenase enzyme activities: possible application to unravel cheating in drugs of abuse testing. Clinical chemistry and laboratory medicine. 2022 Jul 26;60(8):1242-1249

    Expand section icon Mesh Tags

    Expand section icon Substances

    PMID: 35611841

    View Full Text