Urine free beta-hCG and total estriol for Down syndrome screening during the second trimester in an Asian population

Objective: To evaluate second-trimester free beta-hCG and total estriol (E3 ) in the maternal urine as markers for Down syndrome screening in an Asian population. Methods: Free beta-hCG and total E3 were measured in the urine samples of 2 8 Taiwanese Down syndrome pregnancies and 268 unaffected singleton pregnanc ies at 14-25 weeks. Results were normalized to urine creatinine concentrations and converted to multiples of the median (MoM) levels. Gestational ages were estimated by u ltrasound measurements. Results: Median values of free beta-hCG, total E3, free beta-hCG to total E3 ratio, and the free beta-hCG to total E3 MoM rati o in Down syndrome pregnancies were 4.75 MoM, 0.66 MoM, 8.99 MoM, and 9.51, respectively. At a 5% false-positive rate, the observed detection rates we re 36% (ten of 28) with total E3, 71% (20 of 28) with free beta-hCG, 68% (1 9 of 28) with free beta-hCG/total E3, and 71% (20 of 28) with free beta-hCG /total E3 MoM. When combined with maternal age, the expected detection rate s were 65% with total E3, 71% with free beta-hCG, 76% with free beta-hCG/to tal E3, 80% with free beta-hCG/total E3 MoM, and 89% when combining free be ta-hCG, total E3, and maternal age. Conclusion: Urine free beta-hCG and total E3 are useful markers for Down sy ndrome screening during the second trimester in Taiwanese women. (C) 1999 b y The American College of Obstetricians and Gynecologists.