A non-transferrin-bound serum iron in idiopathic hemochromatosis.

The nature of iron in the serum of patients with idiopathic hemochromatosis has been studied utilizing an isotope labeling method and results have been compared with those from normal individuals and patients with other forms of liver disease. Between 2 and 4% of a tracer dose of 59Fe added to normal serum was retained by DEAE Sephadex and has been designated non-transferrin-bound. Alcoholic liver disease, chronic active hepatitis, and iron deficiency have no effect on this fraction. In idiopathic hemochromatosis 34.6 +/- 3.9% of the added iron was not bound to transferrin at diagnosis, representing approximately 700 microgram Fe/liter serum. Treatment lowers this fraction before serum iron concentration falls to normal. The majority of the non-transferrin-bound iron is of low molecular weight and is not bound to albumin. The presence of this fraction may contribute significantly to the development of tissue siderosis.