%0 Journal Article
%T Amniotic fluid gamma-glutamyl transferase for prediction of biliary atresia in cases of non-visualisation of the fetal gallbladder: a retrospective study using a validated analytical platform and local reference range.
%A Cheung TYT
%A Wong NKL
%A Sahota DS
%A Subramaniam SR
%A Lau SL
%A Zhu X
%A Lui WT
%A Chan EKW
%A Kwok YKY
%A Choy KW
%A Leung TY
%A Chan MHM
%A Wong FCK
%A Ting YH
%J Hong Kong Med J
%V 30
%N 3
%D 2024 Jun 5
%M 38835098
%F 1.256
%R 10.12809/hkmj2210567
%X <B>BACKGROUND: </B>The level of amniotic fluid gamma-glutamyl transferase (AFGGT) may help identify biliary atresia (BA) in cases of non-visualisation of the fetal gallbladder (NVFGB). This study aimed to validate a serum/plasma matrix-based gamma-glutamyl transferase (GGT) assay for amniotic fluid (AF) samples, establish a local gestational age-specific AFGGT reference range, and evaluate the efficacy of AFGGT for predicting fetal BA in pregnancies with NVFGB using the constructed reference range.<BR><B>METHODS: </B>The analytical performance of a serum/plasma matrix-based GGT assay on AF samples was evaluated using a Cobas c502 analyser. Amniotic fluid gamma-glutamyl transferase levels in confirmed euploid singleton pregnancies (16+0 to 22+6 weeks of gestation) were determined using the same analyser to establish a local gestational age-specific reference range (the 2.5th to 97.5th percentiles). This local reference range was used to determine the positive predictive value (PPV) and negative predictive value (NPV) of AFGGT level <2.5th percentile for identifying fetal BA in euploid pregnancies with NVFGB.<BR><B>RESULTS: </B>The serum/plasma matrix-based GGT assay was able to reliably and accurately determine GGT levels in AF samples. Using the constructed local gestational age-specific AFGGT reference range, the NPV and PPV of AFGGT level <2.5th percentile for predicting fetal BA in pregnancies with NVFGB were 100% and 25% (95% confidence interval=0, 53), respectively.<BR><B>CONCLUSIONS: </B>In pregnancies with NVFGB, AFGGT level ≥2.5th percentile likely excludes fetal BA. Although AFGGT level <2.5th percentile is not diagnostic of fetal BA, fetuses with AFGGT below this level should be referred for early postnatal investigation.