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Inhibin A measurement using an automated assay platform
Author(s) -
LambertMesserlian G. M.,
Palomaki G. E.,
Canick J. A.
Publication year - 2008
Publication title -
prenatal diagnosis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 97
eISSN - 1097-0223
pISSN - 0197-3851
DOI - 10.1002/pd.1983
Subject(s) - percentile , digital subscriber line , medicine , reproducibility , gold standard (test) , chemistry , mathematics , statistics , chromatography , computer science , telecommunications
Background Second–trimester measurement of maternal serum inhibin A is widely used for Down syndrome screening. To date, only a manual enzyme‐linked immunosorbent assay (ELISA) produced by Diagnostic Systems Laboratories, Inc (DSL) has been available. The objective of this study was to compare the DSL assay with a new automated assay produced by Beckman Coulter, Inc (Access). Methods Residual serum samples from 570 women, who were receiving routine screening for Down syndrome, were retrieved from storage. The Access assay sensitivity, linearity and reproducibility were determined and a method comparison was performed. Inhibin A levels were measured using both assays. Twenty samples from women with confirmed Down syndrome pregnancy were also tested. Results The Access assay had coefficients of variation of less than 10% across the range of values tested, and a sensitivity below 1 pg/mL. The DSL and Access inhibin A assay values were highly correlated ( r = 0.961, r 2 = 0.923), with no apparent outliers. Inhibin A values from the Access assay were a constant 23% lower (95% CI 1–41%) than corresponding values from the DSL assay. Median values from 15 to 20 completed weeks' gestation were computed and found to be consistent with expectations. The weight‐adjusted multiples of the median (MoM) levels in the unaffected pregnancies fit a log Gaussian distribution well between at least the 5th and 95th percentiles with corresponding log standard deviations of 0.1960 and 0.1919 for DSL and Access, respectively. Conclusions With median inhibin A levels appropriately calculated for the Access assay, Down syndrome screening performance is expected to be comparable to that obtained with the manual DSL assay. Copyright © 2008 John Wiley & Sons, Ltd.