Changes of erythropoietic and storage iron components in certain clinical situations as evaluated by ferrokinetic investigations.

A method is described for the quantitative analysis of in vivo organ measurements of 59Fe activity in ferrokinetic investigations. The time-activity curves obtained by sequential surface monitoring over sacrum, liver and spleen can be resolved quantitatively into their different components contributing to the recorded count rate. The analysis is performed in three steps: (1) Count rate contributions from activity in other organs and from scattered radiation from regions outside the organ under investigation are corrected. (2) Distinction is made between radioactivity uptake of the tissue and radioactivity contained in the perfusing blood. (3) The resulting net organ activity is then further resolved into an erythropoietic and a storage iron component by use of a computer program (SAAM-27) and assuming a compartmental model for internal iron exchange. The method was tested in three groups of patients with different haematological disorders and in normal controls. Characteristic patterns of the parameters are found for different diseases and the results correlated well with the clinical findings. It is concluded that in vivo organ measurements of 59Fe activity, when performed and analysed with sufficient care, can provide an insight into the dynamics of the iron exchange that is taking place in an organ. This analytical approach may improve the diagnostic predictions of ferrokinetic investigations.