SERUM FERRITIN IRON, A NEW TEST, MEASURES HUMAN-BODY IRON STORES UNCONFOUNDED BY INFLAMMATION

Serum ferritin protein is an acute phase reactant, We hypothesized tha t serum ferritin protein generated in response to an inflammatory proc ess would have much less iron (Fe) in it than would ''normal'' ferriti n protein, and therefore measuring serum ferritin iron would assess hu man body iron status unconfounded by inflammation. Basic Methods. We m easured serum ferritin iron in 140 clinical samples obtained from the serum banks of Bronx VA Medical Center Hematology and Nutrition Labora tory (Bronx, NY), the CDC Nutritional Biochemistry serum sample bank ( Atlanta, GA), and the sample bank from patients with thalassemia and i ron overload treated at New York Hospital (New York, NY), Each was ana lyzed for three conventional criteria of iron status: serum iron, perc entage of transferrin saturation and ferritin protein. In addition, te sts for inflammation were also performed: C-reactive protein, WBC and transaminases, Seventy-seven patients' sera from 140 screened met each of three consistent criteria for stages of iron status. Serum ferriti n was immobilized by immunoprecipitation with rabbit antihuman polyclo nal antibody bound to agarose and separated from other iron-containing proteins, digested with 0.2 mi of 3N nitric acid and analyzed for iro n content by atomic absorption spectroscopy. Results. Serum ferritin i ron ranged in normal controls from 10 ng to 35 ng Fe/ml. The patients with iron deficiency (4/4) and those in negative iron balance (5/6) ha d values less than or equal to 10 ng, Positive iron balance (8/9) and iron overload (22/22) values were >35 ng/ml, in contrast to 11/19 with inflammation, Seventeen of twenty-two with overload had values >100 n g/ml while only 1/19 with inflammation had such a value, Ferritin iron in ferritin protein was >15% by weight in 14/22 with iron overload bu t in 0/19 with inflammation, Implications of the Work. Serum ferritin iron is a simple, direct measure of iron stores that we propose, in co njunction with measuring serum ferritin protein, as a minimally invasi ve screening procedure for accurately assessing the whole range of hum an body iron status, unconfounded by inflammation.