Enzyme immunoassay of testosterone using nitrocellulose discs as the solid phase

An enzyme immunoassay (EIA) for the measurement of serum testosterone has been developed using nitrocellulose paper discs as the solid support. The paper discs (6 mm diameter) coated with testosterone-specific antibody were incubated with testosterone and testosterone-peroxidase conjugate in glass tubes. The amount of testosterone present in samples could be estimated from the bound peroxidase activity. The assay was validated by comparison with a microtitre plate-based ELISA and a commercial radioimmunoassay (RIA) kit. The correlation coefficient between RIA and EIA was 0.84. No significant cross reactivity was observed with other steroids, except for dihydrotestosterone. The inter- and intra-assay coefficients of variation were 4.4 and 9.6% respectively. The preservation and transport of the coated paper discs are convenient and the overall cost of the method is less than that of other methods.