Screening for Down syndrome using urine hCG free β-subunit in the second trimester of pregnancy

Combining β‐core fragment and total oestriol measurements to test for Down syndrome pregnancies

“…Urine samples were initially diluted 1 to 31 for immunoassay. Further dilutions, 1 to 1, 1 to Cuckle et al (1994) -Core fragment 67 7 >80 (5) Cuckle et al (1995) -Core fragment 294 24 80 (5) Canick et al (1995) -Core fragment 91 14 88 (5) Spencer et al (1996) -Core fragment 400 29 41 (5) Kellner et al (1996) -Core fragment 206 32 72 (5) Isozaki et al (1997) -Core fragment 709 13 62 (5) Cole et al (1997a) -Core fragment 91 14 93 (10) Hyashi and Kozu (1995) Free with -core 150 5 20 (5) Spencer et al (1996) Free -subunit 400 29 58 (5) Cole et al (1997a) Free -subunit 91 14 47 (10) Cole et al (1997b) Free -subunit 709 13 54 (5) Cole et al (1997c) hCG only 91 14 43 (10) Cole et al (1997a) hCG with free 91 14 50 (10) Kellner et al (1996) Total oestriol 206 32 22 (5) Cuckle et al (1995) Total oestrogens 294 24 34 (5) Spencer et al (1992) Free -subunit 2400 90 54 (5) Ryall et al (1992) Free -subunit 1400 57 47 (5) Wald et al (1993) Free -subunit 367 75 55 (5) Spencer et al (1992) hCG with free 2400 90 48 (5) Ryall et al (1992) hCG with free 1400 57 42 (5) Wald et al (1993) hCG 10, and 1 to 100, were made as needed. The total oestriol levels (ng/ml) were also normalized to adjust for variations in the urine concentration by dividing by the creatinine concentration (mg/ml).…”