Stability of free beta-hCG in the routine screening of Down syndrome in the first trimester of pregnancy.

Abstract: Stability of free $-human chorionic gonadotropin in maternal bloodupon storage at ambient and refrigerator temperatures as well as stability underconditions simulating postal transport were studied.A group of 26 women in the first trimester of pregnancy were included in thestudy, blood samples were taken during the routine check-up. Blood samples werealiquoted stored in different conditions that should mimic the transportation andthen analysed for free $-hCG.No significant differences were found in the free $-hCG levels in samples after24 and 48 hours resp., stored in refrigerator (2–8 o C) without separation. Insamples stored in laboratory temperature without separation the averageconcentration increased from 11 to 20%. Six blood samples were stored at 35 o Cfor 5 hours and then in laboratory temperature. In this group the average increaseof results was from 14.3% to 132.2%. Separation of the sera for Down syndromescreening in 4 hours after withdrawal is necessary. Cooling during any storage,including transportation is highly recommended as the preanalytical phase has ahigh impact for the analysis.