ABSTRACT
Objective:To detect the levels of γ-glutamyl transferase (GGT) in the amniotic fluid of normal pregnancies at 19-23 +6 gestational weeks and to analyze the changes in GGT level with gestational age. Methods:This study retrospectively collected the amniotic fluid supernatant from 383 singleton pregnant women (102, 103, 82, 68 and 28 cases at 19-19 +6, 20-20 +6, 21-21 +6, 22-22 +6, 23-23 +6 weeks of gestation, respectively) who underwent amniocentesis for prenatal diagnosis but had normal genetic diagnosis results in Cheeloo Hospital of Shandong University from January 2021 to September 2022. The levels of GGT in the amniotic fluid supernatant were tested and the statistical parameters including xˉ± s, min-max, median ( M), P1, P2.5, P5, P95, P97.5 and P99 values of GGT levels at each gestational week were calculated. GGT were non-normal data and converted into natural logarithms (lnGGT), and a least square linear regression equation was established to analyze the relationship between lnGGT and gestational week. Results:At 19-19 +6, 20-20 +6, 21-21 +6, 22-22 +6, and 23-23 +6 gestational weeks, the xˉ± s of amniotic fluid GGT were (385.8±235.7), (331.8±219.4), (253.7±197.9), (226.7±166.4), and (155.3±96.8) U/L, and the weekly declines were 14.0%, 23.5%, 10.6%, and 31.5%, respectively; the M values were 311.0, 288.0, 199.0, 160.5, and 105.5 U/L, and the weekly declines were 7.4%, 30.9%, 19.3%, and 34.3%, respectively; the P1- P99 were 67.1-1 404.5, 63.2-1 189.1, 36.0-849.8, 44.0-787.3, and 32.0-375.6 U/L, respectively. lnGGT was negatively correlated with gestational age ( R 2=0.148, P<0.001). Conclusions:In normal pregnancies at 19-23 +6 gestational weeks, GGT levels in amniotic fluid decrease with gestational age. Therefore, gestational age should be considered when establishing the reference value for amniotic fluid GGT in normal pregnancies.