The measurement of amniotic fluid alpha 2 macroglobulin by fixed time kinetic immunoturbidimetry

We have developed an assay for alpha 2 macroglobulin in amniotic fluid, based on the technique of Fixed Time Kinetic Immunoturbidimetry. The assay is precise (CV 5% between assays) and has a detection limit of 0.4 mg/l. We have determined the reference range for alpha 2 macroglobulin from 100 amniotic fluid samples from none Neural Tube Defect pregnancies. The data indicates no significant variation of alpha 2 macroglobulin with gestational age and that the results in none Neural Tube Defect pregnancies showed a narrow reference range with a mean of 1.67 mg/l and -/+ 2 SD range of 0.23--3.11 mg/l (99 percentile = 3.65 mg/l). Results in 25 Neural Tube Defect pregnancies are presented.