White blood cells and acute phase reactants in neonatal sepsis.

No single diagnostic test for neonatal sepsis is both rapid and reliable. Combining leukocyte (wbc) counts with acute phase reactants (APR) enhances diagnostic accuracy. The most helpful wbc counts are leukopenia (less than 5.0 x 10(9)/l), increased immature/total neutrophils (greater than or equal to 0.2) and profound neutropenia (less than 1.0 x 10(9)). Of the APR, C-reactive protein responds most rapidly, but alpha 1-acid glycoprotein (orosomucoid), haptoglobin and mini-ESR (greater than or equal to 15 mm/h) are also useful. Rapid, quantitative determinations of APR are now available with nephelometric techniques. Abnormal wbc counts frequently appear before APR changes in group B streptococcal infection. Sequential determinations of wbc counts and APR may provide valuable diagnostic and prognostic information.