Evaluation of the Kodak EKTACHEM clinical chemistry slide for the measurement of bilirubin in newborns.

Measurement of neonatal bilirubin using the Jendrassik-Grof method (x) and the EKTACHEM NBIL assay (y) was compared over a 6-month period in a total of 1191 specimens from 483 patients less than 30 days of age. Linear regression analysis of the data yields a slope of 0.937, an intercept of 0.387, and Sy,x of 0.55 and a correlation coefficient of 0.983 for a total of 1032 specimens from patients less than or equal to 14 days of age and a slope of 1.090, an intercept of 0.002, an Sy,x of 1.03 and a correlation coefficient of 0.950 for a total of 159 specimens from patients greater than 14 days of age. The best correlation between EKTACHEM NBIL assay and the reference Jendrassik-Grof method was observed in samples from patients less than or equal to 14 days of age. Data from patients older than 14 days showed a higher proportional bias and a lower correlation coefficient between the methods. High performance liquid chromatographic analysis demonstrated that patients greater than 14 days of age had a higher incidence of elevated delta-bilirubin. Linearity extends to 200 mg/l. The NBIL assay provides a rapid, precise micromethod that is less sensitive than the Jendrassik-Grof method to the in vitro photo degradation of bilirubin and is not subject to the interference from hemoglobin and lipids. Because delta-bilirubin is not measured by this method, it is only recommended for newborns less than or equal to 14 days of age.

Further improvement of the enzyme-linked antiglobulin test (ELAT) for erythrocyte antibodies.

The enzyme-linked antiglobulin test (ELAT) was found to be nine times more sensitive than the direct antiglobulin test (DAT) in detecting erythrocytes sensitized by IgG antibody in vitro. The release of hemoglobin and other interfering substances from the erythrocytes gave falsely high absorbance values which were corrected by the use of a hemolysis bland with each test. ELAT results showed good precision. With the use of the hemolysis blank, the ELAT should prove to be a useful tool for hospital blood blanks in the detection of weakly reactive allo- and autoantibodies.