Comparison of Different Blood Collection, Sample Matrix, and Immunoassay Methods in a Prenatal Screening Setting

Abstract

We compared how measurements of pregnancy-associated plasma protein A (PAPP-A) and the free beta subunit of human chorionic gonadotropin (fβ-hCG) in maternal blood are influenced by different methods for blood collection, sample matrix, and immunoassay platform. Serum and dried blood spots (DBS) were obtained by venipuncture and by finger prick of 19 pregnant women. PAPP-A and fβ-hCG from serum and from DBS were measured by conventional indirect immunoassay on an AutoDELFIA platform and by antibody microarray. We compared methods based on the recoveries for both markers as well as marker levels correlations across samples. All method comparisons showed high correlations for both marker concentrations. Recovery levels of PAPP-A from DBS were 30% lower, while those of fβ-hCG from DBS were 50% higher compared to conventional venipuncture serum. The recoveries were not affected by blood collection or immunoassay method. The high correlation coefficients for both markers indicate that DBS from finger prick can be used reliably in a prenatal screening setting, as a less costly and minimally invasive alternative for venipuncture serum, with great logistical advantages. Additionally, the use of antibody arrays will allow for extending the number of first trimester screening markers on maternal and fetal health.

Biomarkers for atopic dermatitis

“…130 The higher recovery levels in DBS are probably due to different biomarker concentrations in capillary blood compared to venous blood. Dried blood spots are composed of capillary (whole) blood and contain all blood cells and platelets, which hold many inflammatory analytes, while serum is the fluid remaining after blood coagulation and contains no blood cells or platelets.…”

Dried blood spot measurement of pregnancy-associated plasma protein A (PAPP-A) and freeβ-subunit of human chorionic gonadotropin (β-hCG) from a low-resource setting

“…The measured PAPP‐A concentration in DBS correlated well (correlation coefficient >0.9) but was consistently lower (about 60%) in DBS compared with serum. As DBS is prepared with whole blood rather than serum, a lower concentration would be expected based on literature reports and was previously observed to be about 30% to 40% lower . As the only studies that compared DBS with serum measurements from concomitantly drawn samples (this study and the study of Pennings et al …”

“…Analyses of PAPP‐A and β ‐hCG were performed in a single run with a 1235 AutoDELFIA automatic immunoassay system (PerkinElmer, Turku, Finland), as previously described in detail using automated dissociation‐enhanced lanthanide fluorescent immunoassays for serum and DBS separately (PerkinElmer). For DBS analyses of PAPP‐A and β ‐hCG, one 3.2‐mm spot was punched into 96 well plates using an automated DBS puncher (PerkinElmer).…”

“…In the combined first‐trimester test for aneuploidy, maternal serum levels of pregnancy‐associated plasma protein A (PAPP‐A) and the free β ‐subunit of human chorionic gonadotropin ( β ‐hCG) are combined with ultrasound‐obtained fetal nuchal translucency thickness . PAPP‐A, together with placental growth factor, placental protein 13, the uterine artery pulsatility index, and maternal clinical characteristics, also predicts obstetric complications such as preeclampsia, small‐for‐gestational age fetuses, intrauterine growth restriction, and stillbirth . Other markers including A disintegrin and metalloproteinase 12, and activin A and inhibin A have also been identified as predictors of placental dysfunction …”

“…Recently, the possibility to extend the DBS method to PAPP‐A and β ‐hCG analyses in pregnancy has been explored under controlled conditions . The DBS has the advantage of providing a matrix for biomarker stability, a minimally invasive alternative to venipuncture with a finger prick, and the logistical advantage of allowing sample collection with minimal training.…”