Normative weight-adjusted models for the median levels of first trimester serum biomarkers for trisomy 21 screening in a specific ethnicity

Abstract

ObjectiveTo establish normative weight-adjusted models for the median levels of first trimester serum biomarkers for trisomy 21 screening in southern Thai women, and to compare these reference levels with Caucasian-specific and northern Thai models.MethodsA cross-sectional study was conducted in 1,150 normal singleton pregnancy women to determine serum pregnancy-associated plasma protein-A (PAPP-A) and free β-human chorionic gonadotropin (β-hCG) concentrations in women from southern Thailand. The predicted median values were compared with published equations for Caucasians and northern Thai women.ResultsThe best-fitting regression equations for the expected median serum levels of PAPP-A (mIU/L) and free β- hCG (ng/mL) according to maternal weight (Wt in kg) and gestational age (GA in days) were: and Both equations were selected with a statistically significant contribution (p< 0.05). Compared with the Caucasian model, the median values of PAPP-A were higher and the median values of free β-hCG were lower in the southern Thai women. And compared with the northern Thai models, the median values of both biomarkers were lower in southern Thai women.ConclusionThe study has successfully developed maternal-weight- and gestational-age-adjusted median normative models to convert the PAPP-A and free β-hCG levels into their Multiple of Median equivalents in southern Thai women. These models confirmed ethnic differences.

Ethnic-specific reference range affects the efficacy of quadruple test as a universal screening for Down syndrome in a developing country

“…Moreover, our study and previous studies have shown that race and ethnic factors have an important effect on serum concentrations both in DS and normal fetuses throughout the gestational period [7,[10][11][12]20]. Another study from our institution reported the same evidence from first trimester serum screening for DS [21]. Maternal serum quadruple markers do not have universally applicable levels for screening for DS in all races and ethnicities, and have also been reported in other studies which found differences in normative median serum levels in subgroups of the same country or ethnicity [14,20].…”