Normal values for KL-6 in cord venous plasma of neonates.

Background: KL-6 in umbilical cord blood, including from premature infants, and perinatal factors that may affect these values have not yet been adequately discussed. The authors investigated factors affecting cord venous plasma levels of KL-6 in neonates, and to establish a normal range of values for KL-6 in neonatal cord blood. Methods: Cord plasma levels of KL-6 were measured in 75 neonates, and statistical analysis of factors affecting these levels was performed. A normal range for cord plasma KL-6 levels was calculated by statistical analysis methods based on guidelines by the National Committee for Clinical Laboratory Standards. Results: Data from a total of 75 neonates was analyzed. Gestational age ranged from 25 to 40 weeks (median, 33.4 weeks), and birthweight ranged from 776 to 3760 g (median, 1944 g). There was no statistically significant correlation between cord plasma KL-6 levels with gender, gestational age, birthweight, method of delivery, Apgar score 1 min, and postnatal respiratory distress. The normal range of values for cord plasma KL-6 was 44.3-148.2 U/mL (median, 73.0 U/mL). Conclusion: The cord plasma levels of KL-6 were about half the normal values reported in children and healthy adults and were not affected by various perinatal factors. The authors' findings suggest that plasma KL-6 levels rise when respiratory function is established after birth and tend to further increase with age.