“…Clinical studies have suggested that iron excretion after DTPA closely reflects the size of the stores (Walsh, Perkins, Blackburn, Sanford, and Cantrill, 1963;Powell and Thomas, 1967). However, there is evidence that the iron-DTPA complex dissociates to a considerable and variable extent in vivo (Cleton, Turnbull, and Finch, 1963); as only the iron of the undissociated complex can be excreted, it follows that the iron present in the urine may not be a constant sample of the quantity chelated in the tissues.…”