Modified method for analysis of serum iron.

An improved method for analysis of serum iron is described which is simple, rapid, precise and convenient for routine use in clinical laboratories. Serum proteins are precipitated with trichloroacetic acid-hydrochloric acid solution, with simultaneous release of Fe(III) from transferrin. Fe(III) is reduced to Fe(II) by sodium ascorbate, and Fe(II) is reacted with ferrozine to form a lavender complex, which is measured by spectrophotometry at 562 nm. Measurements of iron in 183 serum samples by this method were compared with measurements by a "direct" spectrophotometric method without without deproteinization, as previously described. Close agreement was obtained in 171 of these 183 pairs of analyses (93.5 percent). Discrepancies (greater than 12 mug per dl) were noted in the remaining 12 serums, which were attributed to interference in direct spectrophotometric analyses of iron, owing to (1) hemolysis, (2) lipemia, (3) jaundice, (4) protracted storage or (5) repeated freezing and thawing of the serums.