Automated quantitative nephelometric latex immunoassay for determining ferritin in human serum

We describe a rapid and sensitive latex nephelometric immunoassay for quantifying ferritin in human serum. This latex immunoassay procedure uses commercially available ready‐for‐use reagents [Tina‐Quant (a) Ferritin, Boehringer Mannheim] that have a long shelf life. The assay consists of incubating the diluted serum sample (5‐fold) for 12 min at room temperature with latex particles covalently coated with anti‐ferritin antibodies, and then quantifying the change of light‐scatter produced. The assay is fully automated on the Behring nephelometer analyzer with a sampling rate of 150 samples/hour. The method has an analytical range of 3 to 260 μg/l. Maximal intra‐ and inter‐assay CVs were 4.0 and 6.2%, respectively. Analytical recoveries ranged from 91.3 to 103.6%. Assay detection limit was less than 3 μg/l. Linearity of the test is given throughout the measuring range. There was no interference from bilirubin (up to 340 μmol/l), haemoglobin (up to 7 g/l), or rheumatoid factor (up to 1,100 IU/ml). Turbid and lipemic samples interfere. This interference may be avoided by pretreating these samples prior to assay. Results correlated well with those obtained by an automated ELISA test (r=0.995) and with those of two commercial RIA methods (r>0.97). This latex nephelometric procedure is a convenient method and represents an interesting alternative to other immunoassays for measuring ferritin in human serum. © 1992 Wiley‐Liss, Inc.