Capillary plasma elastase alpha 1-proteinase inhibitor in infected and non-infected neonates.

Capillary heel prick plasma elastase alpha 1-proteinase inhibitor (E alpha 1-PI) measured by an immunoassay (using commercially available reagents) was examined as an early indicator of neonatal sepsis. Fifty five infants were studied within 24 hours of birth; 60 (including 10 studied on the first day of life) were examined between two and 30 days after birth. Reference ranges for the neonatal period were developed. Raised E alpha 1-PI concentrations (range 440-2600 micrograms/l) were found at the outset of each of the 24 infectious episodes including five with concomitant neutropenia. On the first day of life, obstetric and neonatal complications were also associated with high concentrations (range 190-2400 micrograms/ml). In infants who survived infection, E alpha 1-PI normalised with antibiotic treatment. It is concluded that capillary heel prick plasma is suitable for E alpha 1-PI testing and raised concentrations provide a sensitive but non-specific index of infection in the first 24 hours after birth. Sequential testing may provide early warning of infectious complications and serve as a guide to the cessation of antibiotic treatment.