Changes in transferrin glycosylation during pregnancy may lead to false-positive carbohydrate-deficient transferrin (CDT) results in testing for riskful alcohol consumption

BackgroundAn alcohol-induced change in serum transferrin glycosylation, termed carbohydrate-deficient transferrin (CDT), is widely used as a biomarker of heavy long-term drinking. This study examined the transferrin glycosylation profile and the risk for false-positive CDT results during pregnancy.MethodsSerum samples were collected from 24 healthy pregnant women starting in gestation week 9–21, throughout pregnancy, and 8 or more weeks after delivery. Altogether 171 sera (5–9 samples/person) were analysed. Transferrin glycoforms were quantified as a percentage of total transferrin, using an HPLC candidate reference method for CDT.ResultsDuring pregnancy, the relative disialo-, pentasialo- and hexasialotransferrin levels increased gradually, whereas trisialo- and tetrasialotransferrin were reduced. This effect was most pronounced in the third trimester. For disialotransferrin, the main target in CDT testing, initial values of 1.07 ± 0.17% (mean ± SD) increased to 1.61 ± 0.23% before delivery (~ 50% increase). Nine (38%) pregnant women reached %disialotransferrin values ≥ 1.7% (97.5th percentile for controls) but all results were < 2.0%. In the postpartum samples, all glycoform levels had returned towards the starting values.ConclusionsThese results suggest that the cutoff for %disialotransferrin and %CDT employed to indicate heavy long-term drinking need to be raised slightly in pregnant women, to minimize the risk for false-positive results on CDT testing.