APPLICATION OF BIOMARKERS IN EVALUATION OF FETAL LUNG MATURITY

Abstract

Summary: In the process of maturation, alveolar epithelial cells produce surface-active material (surfactant) which consists mainly of phospholipids and, although to a significantly lesser degree, neutral lipids, proteins and carbohydrate. Pulmonary surfactant is synthesized in alveolar type-II granular pneumocytes and »packed« as lamellar bodies. Before delivery, the lamellar bodies diffuse through the bronchial tree into the amniotic fluid. Parameters which indicate the maturity of lungs, except the concentration of lamellar bodies, also are observed in the ratio against the quantity of surfactant with other components of the amniotic fluid (sphingomyelin and albumin). The study concerns the determination of the surfactant-to-albumin ratio and the lamellar body count in the amniotic fluid as predictors of fetal lung maturity. The research involved 90 pregnant women with gestational age from 32 to 40 weeks. The samples of the amniotic fluid were obtained by amniocentesis and they were filtrated through special filters. The surfactant-to-albumin ratio was measured by the Fetal Lung Maturity II (FLM) test, on a TDX instrument (ABBOTT). The concentration of lamellar body count was measured on a hematology cell counter by the platelet channel, on the Cell Dyn 3700 instrument (ABBOTT). The average value of S/A ratio was 55.11 mg/g (min=6.96 mg/g, max=112.00 mg/g). The surfactant-to-albumin ratio of less than 39.00 mg/g predicts respiratory distress syndrome with the probability of 92%. The average value of LB was 69.4 × 109/L (min=4.2 × 109/L, max=199.0 × 109/L). Lamellar body concentration of 34.0 × 109/L or less predicts respiratory distress syndrome with the probability of 93%. The surfactant to albumin ratio increased with gestation (r=0.373, p<0.005), as did lamellar body concentration (r=0.934, p<0.001). The two tests correlated with each other, r=0.341, p<0.005. In 90 patients delivered within 72 hours the surfactant-to-albumin ratio and concentration of the lamellar body correctly predicted six cases of the respiratory distress syndrome. There was a high degree of positive correlation between gestational age and surfactant-to-albumin ratio, as to lamellar body concentration.