CAP Comprehensive Chemistry. Serum iron survey.

Approximately 1,600 participants replied to a special questionnaire about the serum iron determination used in their laboratories. The categories covered were (1) sample preparation, (2) system, (3) detection method, (4) reducing reagent, and (5) standards. Those using AutoAnalyzer methods uniformly had the highest reported values. The lowest values were reported by those using methods without protein removal. Whether this is a positive bias by the AutoAnalyzer group or a negative bias by methods without protein removal, or both, cannot be determined by this study. Hydroxylamine users reported lower results than others. No difference between the three commonly used chromogenic reagents, bathophenanthrolene sulfonate, tripyridyl-triazine, and ferrozine, could be demonstrated. Protein-based standards should be used when a method is found to be affected by protein. How to determine the assay value is an important problem yet to be solved.