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A high-sensitivity assay for amniotic fluid insulin at 14-20 weeks' gestation
M W Carpenter1, J A Canick, J A Star
1Department of Obstetrics and Gynecology, Brown University, Providence, Rhode Island, USA. mcarpent@wihri.org
Obstetrics and Gynecology
|November 5, 1999
Summary
This study validates a sensitive immunochemiluminomimetric assay for measuring amniotic fluid (AF) insulin in the second trimester. The assay demonstrates reliable precision and sample stability, supporting its use in clinical research.
Area of Science:
- Biochemistry
- Reproductive Medicine
- Assay Development
Background:
- Second-trimester amniotic fluid (AF) insulin concentrations are important for understanding fetal development.
- Accurate measurement of AF insulin requires sensitive and precise assays with stable sample handling.
Purpose of the Study:
- To evaluate the sensitivity, precision, and sample stability of an immunochemiluminomimetric insulin assay for AF.
- To determine the fetal age distribution of AF insulin concentrations in the second trimester.
Main Methods:
- Assayed fresh AF specimens from 576 gravidas (14-20 weeks' gestation).
- Assessed sample stability through storage at 4°C for 14 days and -20°C for 70 days.
- Evaluated assay performance including detection limit, linearity, and spike recovery.
Main Results:
- The assay reliably measured AF insulin down to 0.03 microIU/mL.
- Insulin concentrations followed a log10 Gaussian distribution (0.24-7.41 microIU/mL) in 14-20 week AF.
- No significant insulin loss was observed after storage at 4°C for 14 days or -20°C for up to 70 days.
Conclusions:
- The immunochemiluminomimetric insulin assay is sensitive and precise for measuring low AF insulin levels.
- The assay's reliability supports its use in investigating clinical associations of second-trimester AF insulin.
- AF insulin assays can be reliable using specimens stored for up to 70 days.