Increasing hCG concentrations during storage at +4°C with the Bayer Centaur Total hCG method

摘要

Background The interpretation of changes in serum human chorionicngonadotropin (hCG) concentrations in early pregnancy requires a knowledge of thenday-to-day imprecision of the method at the concentrations measured. We thereforenattempted to determine the analytical imprecision of our total hCG method over an4-week period at concentrations up to 20 000 IU/L.nMethods Serum specimens with hCG concentrations between 100 and 20 000 IU/Lnwere collected during early pregnancy and analysed using the Bayer Centaur TotalnhCG method at weekly intervals after storage at +48C and 7208C.nResults The reproducibility of hCG results over a 4-week period in refrigeratednspecimens with an initial hCG concentration below 1000 IU/L was poor (meanncoefficient of variation紏17.4%) and there was an apparent increase in serum hCGnconcentrations of up to 68%. Similar changes occurred in some specimens stored atn7208C. Further experiments confirmed that significant increases can occur duringnthe first week following specimen collection.nConclusions Total hCG concentrations in serum specimens collected during earlynpregnancy increase significantly during storage when measured by the BayernCentaur Total hCG method, possibly due to a conformational change innhyperglycosylated hCG. When this method is used for monitoring early pregnancy,nspecimens should ideally be analysed on the day of collection.