Cost containment in laser immunonephelometry

Abstract

Cost of measuring serum specific proteins on the Hyland Laser Nephelometer (PDQ) is reduced from $1.60 (U.S.) per test to an average of 35 cents (range: 18–76) per patient result by preparing dilutions in polyethylene glycol of antibodies that are available commercially (Dakopatts a/s, Denmark). An expensive, cumbersome dilutor-dispenser used in the prescribed method is replaced by simple pipetting procedure. Antibodies employed were verified to be monospecific immunoglobulins raised each against one 11 human specific proteins studied, namely albumin, orosomucoid, alpha-1-antitrypsin, alpha-2-macroglobulin, haptoglobin, transferrin, beta-1-C-globulin (C3), beta-1-A-globulin (C4), and immunoglobulins IgG, IgA and IgM. Development of relative light scatter, measured nephelometrically, was shown to be stabilized within 40 minutes of adding sample to antibody. Linearity of graphs for six calibrating references in each method, relating concentration of standard to nephelometric relative light scatter, was excellent. Furthermore, very reproducible results were obtained from day-to-day (CV of 2 – 10%) for standard concentrations within ranges usually encountered clinically. Precision for Hyland Immunochemistry Control, measured against Hyland calibrating references, was acceptable (average CV: 7.6%; range: 5 – 11%). Due to lack of uniformity found previously in expressing concentration in different batches of Hyland Calibrators and Accuracy Controls, correlation of results obtained with Hyland antibodies versus those obtained with Dako antibodies was not carried out. Intermanufacturer comparison of results of the 11 proteins in commercial immunochemical quality control standards from Hyland and two other sources (Atlantic Antibodies, Behring Diagnostics) was disappointing. However, precision in measuring the same 11 specific proteins in controls of three commercial sources (Hyland, Atlantic, Behring) studied with Dako antibodies and Hyland calibration (average CV of 7.6, 10.5 and 11.1% respectively) was similar to that previously reported using Hyland antibodies and Hyland calibration (corresponding average CV of 7.6, 10.7 and 12.5% respectively). Dako antibodies were found to be well suited for use on the Hyland Laser Nephelometer. Need for proper standardization of calibration between various manufacturers is again emphasized.