Quantitative measurement of iron stores with diethylenetriamine penta-acetic acid.

The use of the chelating agent diethylenetriamine penta-acetic acid (DTPA) for measuring body storage iron was investigated in patients with iron excess whose stores could be determined by venesection. Iron excretion after DTPA bore a close semi-logarithmic relationship to body iron stores when these were increased. The excretion of DTPA-bound (59)Fe was similarly related to the size of the stores, indicating that the increased iron excretion produced by DTPA in iron overload states reflects both increased tissue iron available for chelation and greater stability of the iron-chelate complex. Evidence was obtained that injected (59)Fe-DTPA could be used as a marker for chelated tissue iron enabling the DTPA-chelatable body iron pool to be calculated. There was a highly significant correlation between DTPA-chelatable iron and body storage iron. The regression intercept approximated to the origin, implying a specific relation between the DTPA effect and storage iron. The SE of the mean estimate for storage iron on DTPA-chelatable iron was 0.25 g (5.6%). Mean storage iron values of 392 mg for males and 243 mg for females were predicted from the findings in control subjects.