Abstract

Chromium (III) has recently been shown to be an essential trace mineral in rats, being required for normal function of insulin in controlling glucose metabolism. Chromium is transported in the body bound to transferrin, where it binds competitively with iron. Hemochromatosis is an iron storage disease in humans characterized by highly saturated transferrin levels and sometimes by diabetes. We postulated that the diabetes may be due to exclusion of chromium by iron at metabolic binding sites. 51Cr(III) was administered i.v. to 5 normal males, 6 patients with hemochromatosis prior to therapeutic removal of iron, and 5 patients with varying levels of iron loading. The retention of 51Cr was measured with a whole-body counter for 8 mo and blood levels were measured for 40--80 days. Analysis of the whole-body retention curves revealed 3 exponential components with T1/2s of .56 days, 12.7 days, and 192 days; the blood curves had 4 components with T1/2s of 13 min; 6.3 hr, 1.9 days, and 8.3 days. The T1/2s were not significantly different between the normals and patients. The coefficients of these components however, were significantly lower for the long T1/2 components in the iron-loaded patients, demonstrating reduced retention of 51Cr as postulated. Whether this reduced retention of chromium is causally related to diabetes in hemochromatosis and whether abnormal chromium metabolism is involved in endogenous diabetes, thus, becomes an important question for future study.