Serum ferritin in the elderly.

A two-site immunoradiometric assay for human ferritin has been developed using antibody-coated polystyrene tubes. Serum ferritin was measured in fifty-four men and women aged 73 years. The geometric mean was 166 micrograms/l for thirty-one men and 161 micrograms/l for twenty-two women. One woman was excluded from the statistical calculations. Twenty-eight of the subjects had earlier participated in a study of food consumption by the duplicate portion technique. There was a significant correlation (r = 0.44, P < 0.01) between the food iron intake and the serum ferritin values. A reference material of men and women aged 18-55 years was also analysed. The geometric mean for males was 170 micrograms/l with a 95% confidence range of 46-637 micrograms/l. The female controls were found to have significantly lower values (geometric mean 51 micrograms/l, 95% confidence range 10-260 micrograms/l) than both the older women (P < 0.001) and the male controls (P < 0.001).