Measurement of ferritin levels: comparison of a commercial IRMA to an in-house ELISA method.

The purpose of this study was a comparison of a commercial IRMA to an in-house ELISA method. Because IRMA methods are considered to be very sensitive and results of these assays are widely accepted, the ferritin levels of 378 school children were determined in parallel with a commercial IRMA kit (Becton Dickinson Co., Orangeburg, NY) and the ELISA. For organizing reasons plasma was used for the ELISA, whereas serum was used for the IRMA. Regression analysis of the pairs of values, taking the IRMA reading as the independent variable, yielded a coefficient of variation r=0,90 (Spearman, two-tailed, p=0,01) and the straight line y=0,99x+3,13. Using this ELISA technique described by DAKO, ferritin levels in plasma were, on average, 13,2% higher than in serum taken at the same time. The ELISA technique described was found to have good accuracy and the speed and ease with which it may be carried out makes it suitable for a large number of samples.