Evaluation of the Dual Test using PAPP-A and Free beta-hCG in First Trimester as a Prenatal Screening Test for Down Syndrome / 대한임상병리학회지

ABSTRACT

BACKGROUND: Dual test has been reported to be a useful first trimester screening test for Down syndrome and is comprised of measuring two serum parameters; pregnancy associated plasma protein A(PAPP-A) and free beta chorionic gonadotrophin(beta-hCG). This study was performed to investigate the distribution of these two parameters in Korean pregnant women and compare its significance with that of Triple test which is a second trimester screening test and being more commonly used in Korea. METHODS: For the Dual test, serum PAPP-A and free beta-hCG were each measured by radioimmunoassay(AMERLEX-M kitTM) in 2,526 first-trimester pregnant women. Triple test was done in 7,007 second-trimester pregnant women. RESULTS: The median value of PAPP-A was 9.3, 12.5, 18.1 and 26.6 IU/mL, and that of free beta-hCG was 47.8, 35.4, 29.4 and 29.3 nmol/L in 10th, 11th, 12th and 13th gestational week, respectively. The Dual test was positive in 7.8%(198/2,526), while the Triple test was positive in 3.0%(208/7,007). Among 87 Dual test positive cases, Down syndrome was diagnosed in three cases(3.5%), while 71 Triple test positive cases, seven cases(9.9%) were Down syndrome. Among 1,316 cases who had both the Dual and Triple test, 1,300(98.8%) were both negative, and two(0.2%) were both positive, showing 99% of concordance rate. CONCLUSIONS: These results showed a possibility that the Dual test could be used as a valuable first-trimester screening test for Down syndrome in our country.