Evaluation of a Dried Blood Spot Assay to Measure Prenatal Screening Markers Pregnancy-Associated Plasma Protein A and Free β-Subunit of Human Chorionic Gonadotropin

Abstract

BACKGROUND: First-trimester prenatal screening for aneuploidy by use of dried blood spots (DBSs) may offer practical benefits in settings where the instability of intact human chorionic gonadotropin (hCG) is problematic. We evaluated a DBS pregnancy-associated plasma protein A (PAPP-A) and free ␤-subunit of hCG (free hCG␤) dual assay and compared it to serum screening.

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

“…f β -hCG recovery is increased in DBS compared to serum storage, corresponding to previous data [16]. This is independent of venous (156%) or finger origin (151%) (Table 1).…”

“…Different recovery or amounts in DBS compared to serum are probably due to the fact that measurements in DBS are actually measurements in blood and not in serum. This difference between DBS and serum was described earlier and has been attributed to f β -hCG subunit release by dissociation of hCG occurring faster in blood than in serum [2, 16]. On the other hand, similar dissociation of PAPP-A from the heterotetrameric complex with MBP would lead to conformation changes and a decreased detection by assay antibodies [2].…”

“…On the other hand, similar dissociation of PAPP-A from the heterotetrameric complex with MBP would lead to conformation changes and a decreased detection by assay antibodies [2]. To cope with this in screening is to prepare separate mathematical equations for the relationship between gestational age and median concentrations measured in blood spots [17] and to adapt risk calculation algorithms to take into account differences in population distribution parameters [2, 16]. Thus, as a sample matrix, serum and DBS are suitable (provided calculations appropriate for the laboratory protocol are applied) with DBS offering logistical and storage stability advantages.…”

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

“…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.…”

Sensitive Quantification of Igf-1 and its Synthetic Analogs in Dried Blood Spots

“…Several methods have been developed to measure clinically relevant proteins in DBS by immunoassay, such as hCG, thyroglobulin, and prostate-specific antigen [11][12][13]. More recently, LC-MS/MS methods to measure moderate-to-high abundance and therapeutic proteins in DBS after trypsin digestion have been reported [14][15][16][17][18].…”